The Supplier Map
There is no single best place to buy robot parts. A working supplier map splits the order by category: electronics, mechanical, chips, and bulk hobby.
The Bot Scout supplier test asks three questions per order: does the seller publish real datasheets, does the seller ship to my country, and does the seller stock the part today (not next month). If all three are yes, the price difference between suppliers is usually less than the shipping.
For where the parts go, cross-reference the robotics for beginners guide and the Arduino robot kits guide before ordering.
| Supplier | Best for | Documentation | Ships (US/International) |
|---|---|---|---|
| Adafruit | Sensors, boards, LED, wearables | Excellent (tutorials + datasheets) | US, international |
| SparkFun | Breakout boards, GPS, wireless | Excellent (hookup guides) | US, international |
| Pololu | Motors, drivers, encoders, chassis | Excellent (schematics) | US, international |
| ServoCity | Actobotics mechanical, servos | Very good | US, international |
| RobotShop | Kits, drones, arms, wide selection | Good | US, EU, CA |
| DFRobot | Boson, Gravity sensors, kits | Good (wiki) | International |
| Digi-Key | Chips, passives, connectors | Full datasheets | Global |
| Mouser | Chips, passives, connectors | Full datasheets | Global |
| McMaster-Carr | Fasteners, raw stock, mechanical | Engineering-grade | US (primary) |
| AliExpress | Bulk, clones, hobby servos | Poor | Global (long lead times) |
Motors, Servos, and Drivers
Pololu is the honest first stop for hobby DC motors, gearmotors, and stepper motors under 100 W. Their catalog includes matched motor drivers, encoder options, and mounting brackets, all documented with schematics.
For servos, ServoCity and Adafruit stock the mainstream hobby options (SG90, MG996R, Dynamixel). ServoCity also stocks the Actobotics mechanical system for building around them.
For metal-gear digital servos used in DIY robot dogs and arms (LX-224, LX-16A), Hiwonder is the primary source; Amazon resells them. Expect $12-25 per servo.
Sensors
For any I2C or SPI sensor under $20 — IMUs, ToF, IR, light, color, temperature — start with Adafruit or SparkFun. Both write hookup guides that make the difference between a two-hour build and a two-day debugging session.
For modular no-solder sensors, DFRobot's Gravity and Boson lines are the cleanest ecosystem. The connectors are keyed, the wires are color-coded, and the price is competitive.
For cheap ultrasonic (HC-SR04) and IR line sensors (TCRT5000) in bulk, Amazon and AliExpress are fine. Expect $2-5 per sensor and a wider quality range.
Chassis, Wheels, and Mechanical
Chassis kits (acrylic 2WD, aluminum 4WD, tracked tank) are stocked by Pololu, Adafruit, and RobotShop under $50. Mecanum wheels are stocked by Pololu, Nexus Robot, and some Amazon sellers.
For custom mechanical work — brackets, fasteners, extrusion, bearings — McMaster-Carr is the industry standard for US builders. Their catalog is engineering-grade and their delivery is same-day in most metros.
For 3D-printed alternatives, see the 3D-printed robot projects guide. STL sources cost nothing; filament costs $20-30 per kg.
- Chassis under $50: Pololu, Adafruit, RobotShop.
- Extrusion and Actobotics: ServoCity.
- Fasteners and raw stock: McMaster-Carr.
- Custom cut aluminum or PCB: SendCutSend, JLCPCB, PCBWay.
- 3D-printed parts: your own printer, or Craftcloud / Shapeways.
Batteries, Wire, and Connectors
18650 lithium cells and holders are stocked by Adafruit, Pololu, and Battery Junction. Buy protected cells from a reputable seller — Battery Junction or Fasttech — not from an unbranded Amazon listing.
LiPo packs and chargers are stocked by HobbyKing, Amazon, and RobotShop. If the kit does not specify a charger, buy a balance charger; unbalanced charging kills LiPo packs.
For wire, JST-XH and Dupont connectors, ferrules, and heat shrink, buy an assortment kit from Amazon and a real crimper. A $30 ratcheting crimper pays for itself in one project.
Realistic Price Ranges
A working sensor is $2-15. A brand-name breakout of the same sensor is $6-30. Pay the breakout price the first time; buy the bare sensor once you know how it fails.
A hobby DC gearmotor is $6-20. A metal-gear servo is $12-30. An 18650 protected cell is $5-10. A LiPo balance charger is $30-80.
For total build cost, use the DIY robot cost calculator. Expect $80-300 for a wheeled build, $150-600 for an arm, $300-2000 for a quadruped.
Bottom Line
The best supplier depends on the part. Adafruit and SparkFun for sensors and breakouts, Pololu for motors and drivers, ServoCity and McMaster for mechanical, Digi-Key and Mouser for chips, AliExpress for bulk when you can wait.
Split your order by category, pay for documentation the first time, and keep a spares shelf with cells, servos, and jumper wires.
FAQs
Where is the best place to buy robot parts online?
Adafruit and SparkFun for sensors and breakouts, Pololu for motors and drivers, ServoCity for mechanical, Digi-Key and Mouser for chips, and RobotShop for wide-selection kits. AliExpress is fine for bulk hobby parts if you can wait on shipping.
Where can I buy replacement servos for a robot kit?
For hobby servos (SG90, MG996R), Adafruit, ServoCity, and Amazon all stock them. For Hiwonder metal-gear digital servos (LX-224, LX-16A), Hiwonder itself and Amazon are the primary sources.
Is AliExpress safe for robot parts?
For low-cost non-critical parts (jumper wires, common resistors, HC-SR04 sensors), yes. For anything safety-critical like LiPo batteries, chargers, or motor drivers you plan to push near their limits, buy from a supplier that publishes real datasheets.
Where do I buy raw aluminum or steel for a robot chassis?
McMaster-Carr is the US standard for engineering-grade metal, extrusion, and fasteners. SendCutSend does custom laser and waterjet cutting from uploaded DXF files. Local metal supply houses stock stock lengths for pickup.