Since my prior cost breakdown post, I’ve invested a little more in this project.  Thankfully, this hasn’t been a project where I’ve been throwing money at the end goal.  Overall, it’s been incredibly cheap with the cost of failure at the most delicate points being quite low.this help in choosing the steppers and power adapter.  Here’s what I bought and from where:

• 1/10/2012
• Adafruit Industries
• 9 VDC 1000mA regulated switching power adapter – UL listed – $6.95
• Stepper motor – 200 steps/rev, 12V 350mA – 2x $14.00/motor
• Micro servo – $6.00
• Arduino Uno R3 (Atmega328 – assembled) – $29.95
• I opted for USPS Priority Mail, total expenditure: $82.85
• MakerBot
• Adafruit Motor/Stepper/Servo Shield for Arduino Kit v1.0 – $12.00 (Usually $20 elsewhere!)
• I opted for USPS Priority Mail, total expenditure:  $20.45
• 1/26/2012
• MakerBot
• Adafruit Motor/Stepper/Servo Shield for Arduino Kit v1.0 – $12.00
• USPS Priority Mail, total expenditure:  $20.45
• 1/28/2012
• Hardware store – items picked up while there for other items
• Box of eyescrews – $1.79
• Soldering iron tips – $6.99
• With tax, $9.55
• 2/5/2012
• Hardware store – special trip just for this one thing¹
• Plywood – 2′x4′x0.5″ – $12.99
• With tax, $14.13
• Stuff
• This is just a bunch of stuff I have lying around the house.  Chances are you probably do as well.
• 3D printer, ABS plastic
• Monofilament line
• Butcher paper, A4 paper
• Blue tape, scotch tape, duct tape
• A variety of pens
• A variety of 3mm bolts, 3mm nuts, random screws
• Solder, soldering iron, bits of wire, shrink tubing
• Wooden box, now unused
• Ziplock baggie with spent batteries
• Total expenditure: $147.43

Right now the robot is probably close to its final form and I don’t anticipate any further expenditures.  Someone who has a box of electronic stuff could almost certainly build this robot for next to nothing.  Many other people have spare Arduinos, steppers, stepper controllers, and power supplies.  If I just purchased the bare minimum for this project and used scrap stuff from around the house, I probably could have built this robot even cheaper.

1. I couldn’t think of anything else I couldn’t live without!! [↩]