In August we ran a simple test on an industrial robot arm: take a dealer's spare-parts catalogue, add up the major assemblies, and compare the total with the price of a new machine from the same dealer. For a Universal Robots UR5e, six replacement joints came to $46,071 — more than a new UR5e costs. That was a striking result, but it was one machine class, from one vendor, with an unusually vertical spare-parts operation. The obvious question was whether it generalises.
So we ran the same test on something as different as we could find: an agricultural spray drone. Different manufacturer, different country, different price point, different industry, different distribution model. Here is what the numbers say.
The method
Agri Spray Drones, a US EAVision dealer, publishes its entire service catalogue — several hundred SKUs with live add-to-cart prices, from a $0.03 plastic gasket to a $2,999 flight battery. On 5 August 2026 we pulled the full catalogue (2,000 listings, currency confirmed USD via the store's cart endpoint) and built a bill of materials for the EAVision J100 from that dealer's own part prices.
The comparison price is the J100 airframe at $21,999, listed by a second US dealer, Drone Spray Pro, on the same day. We used the airframe price rather than the $32,995 flight-ready package deliberately: the package includes extra batteries and ground support that a parts rebuild would not reproduce, so comparing against it would flatter the rebuild.
Quantities follow the aircraft: four motors, four ESCs, four arms and four beams; one of everything else. Where the dealer lists two variants of a part we used the V1 configuration throughout.
The bill
| Subsystem | Line items | Cost | Share |
|---|---|---|---|
| Power | Flight battery $2,999 + charger/cooler $2,999 + battery cover $482 | **$6,480** | 25.1% |
| Flight electronics | Main controller $2,263, transmission module $591, remote $1,600, FPV $231, forward lidar $1,727, ground radar $998, 360° radar $547, GPS antennas $175, main/sub antennas $160 | **$8,292** | 32.1% |
| Propulsion | 4 motors @ $628 = $2,512, 4 ESCs @ $628 = $2,512, full propeller set $789 | **$5,813** | 22.5% |
| Spray system | 4-nozzle assembly $1,814, 45 L tank assembly $1,190, pump $141, flowmeter $197, solenoid valve $92 | **$3,434** | 13.3% |
| Structure | 4 carbon arm tubes $472, 4 beams $196, landing gear $73 + kit $338, 4 motor bases $196, rear bracket $401, front module bracket $49, three covers $69 | **$1,794** | 6.9% |
| **Total** | **$25,813** | 100% |
$25,813 to rebuild, $21,999 to buy new. The parts cost 17.3% more than the machine.
What this confirms
The UR5e result was not a Universal Robots quirk. Two machines that share nothing — a $39,000 Danish collaborative arm sold through industrial distributors, and a $22,000 Chinese spray drone sold through farm-equipment dealers — both price their spare parts at or above the cost of the whole product.
This is worth stating plainly because the intuition runs the other way. Buyers routinely assume that a machine carries an assembly-and-margin premium over its constituent parts, and that a rebuild is therefore the cheap path. In robotics it is not. The complete machine is the discounted SKU; the parts are the full-margin ones.
The practical consequence: any maintenance model that assumes you can keep a robot flying indefinitely by replacing subsystems is understating cost. On these numbers, a J100 that needs its power system and its sensor stack replaced once has consumed $9,752, or 44.3% of a new airframe, and still has original motors.
Where the money actually sits
Three findings from the subsystem split.
One battery and one charger are 27.3% of the aircraft. $5,998 of a $21,999 machine, for two items that are consumables in everything but name. This is also the cleanest explanation for the gap between the $21,999 airframe and the $32,995 flight-ready package — $10,996 buys roughly the extra batteries, charging and field power that make the aircraft into an operation.
Sensing is 14.9%, and it is not one sensor. Forward lidar $1,727, ground radar $998, 360° obstacle radar $547 — $3,272 across three separate devices. When a spray drone spec sheet says "obstacle avoidance", it is describing a stack, and replacing the cheap one and the expensive one are very different events.
Structure is 6.9%. The frame, arms, landing gear and covers — everything a farmer would actually break in a hard landing — total $1,794. The good news for operators is that crash damage confined to structure is cheap. The bad news is that it almost never is: an arm strike takes a $628 motor and a $628 ESC with it, and one arm's worth of propulsion damage costs more than the entire airframe structure.
The J150 is a different cost class, not a bigger J100
The same catalogue prices the J150 line, and the scaling is not gentle:
| Part | J100 | J150 | Delta |
|---|---|---|---|
| Propulsion motor | $628 | $1,236 | **+96.8%** |
| Forward-looking lidar | $1,727 | $2,588 | +49.9% |
| Flight battery | $2,999 | $3,999 | +33.3% |
| Remote controller | $1,600 | $2,500 | +56.3% |
Against purchase prices of $21,999 (J100 airframe) and $40,495 (J150 basic package), the parts inflate faster than the headline on the item that matters most: a set of four J150 motors is $4,944 against $2,512 for the J100. If you are choosing between the two aircraft on purchase price alone, the running-cost gap is wider than the sticker gap suggests.
A cross-brand check
The same dealer stocks DJI Agras parts, which lets us compare like with like at one seller on one day:
| Part | EAVision J100 | DJI Agras T50 |
|---|---|---|
| Propulsion motor | $628 | $464 (10033) |
| Forward radar / lidar | $1,727 | $2,066 (front radar module) |
| Core control board | $2,263 (main controller) | $1,340 (core board module) |
EAVision's motor is 35.3% more expensive than DJI's, and its main controller 68.9% more, while DJI's front radar module is the pricier item. This matters because EAVision's airframe is also the more expensive one at this dealer ($21,999 against $16,499 for a T50). The challenger brand is not the cheap option on purchase price or on parts.
Our reading
The pattern across both tests is that spare-parts pricing in robotics is not a discount on the machine, it is a premium on it — reliably, across machine classes, price points and continents. For anyone building a total-cost model, the safe assumption is that the parts bill for a full rebuild lands somewhere between 100% and 120% of a new unit, and that the subsystems most likely to need replacing (power, sensing) are the expensive half of it.
The corollary for buyers is that the negotiation worth having is not on the machine price. It is on what the batteries cost in year three.
Sources
All prices read 5 August 2026 from live catalogues with add-to-cart; currency confirmed USD via cart endpoints.
- Agri Spray Drones service catalogue, EAVision and DJI Agras parts: https://shop.agrispraydrones.com/products/ea-vision-j100
- Drone Spray Pro, EAVision J100 airframe listing ($21,999): https://dronespraypro.com/products/eavision-j100
- Drone Spray Pro, EAVision J100 flight-ready package ($32,995): https://dronespraypro.com/products/eavision-j100-base-package
- EAVision J100 official specifications: https://www.eavision.com/spraying-drones/j100
- Our prior test on a Universal Robots UR5e: spare parts as a share of TCO
- Model line and package pricing: EAVision spray drone price guide
Limitations. This is one dealer's catalogue on one day, and the bill of materials is ours, not EAVision's — a factory BOM would include fasteners, harnesses and assembly labour we have deliberately excluded, which means $25,813 is a floor rather than a complete rebuild cost. Quantities are inferred from the airframe configuration and not confirmed with the manufacturer. Cross-brand part comparisons match on function, not on specification; a DJI motor and an EAVision motor are not interchangeable and may not be equivalent in output. Prices at other dealers will differ.
