So if you are looking for an entry level project to cut your teeth on or a scalable platform for your wheeled robotic ambitions, I hope you find this instructable helpful and look forward to seeing how everyone improves upon it.
I conducted a search for similar instructables prior to writing this up and found a couple others (here and here) that are quite good and worth checking out as well. The main difference between my 'able and theirs' is that I used three PING sensors vice one to give our robot greater flexibility in regards to obstacle avoidance. The drawback here is of course the obvious and non-trivial increase in cost.
The robot navigating it's way down the sidewalk.
Step 1: Gather your supplies
1:12 Chevrolet Silverado RC Truck - $40
Arduino UNO - $35
SEEED Motor Shield - $15
PING Ultrasonic sensor (x3) - $20 each
U Mold Plastic - $39
9V battery leads - $1
Adapataplug Tip "M" - $4 (or any 5.5 mm outer Diameter, 2.1 mm inner diameter plug)
22 AWG Wire
Heat shrink tubes
Small tip screwdriver
Lighter (or heat gun for heat shrink)
Dremel or other small drill