First, you're going to need a deck. If you're working on a budget, go to Walmart or Academy Sporting Goods or similar and pick up something cheap for around $20. The above deck is a bustin mini maestro, which I think I got for $80-90. The primary difference is quality of the build / size; this is a longboard deck (though a small one) and it gives me more room to work with. You can get away with using a cheapo $20 skateboard, though.

Next get some trucks. These are inexpensive Paris trucks off Amazon.

If you get a cheapo-skateboard, they'll come with wimpy plastic wheels. You need big, beefy ones if you're going to do some cruising. I recommend 70mm or so sized wheels, also off Amazon. They often come with bearings as featured above, but check out any online skateboarding / longboard resources if you're confused how to put all this stuff together.

The heart of this (and most EV projects) build is the brushless outrunner motor. Hobbyking is probably still your best bet for finding these. You'll want something with a relatively low kv rating (low kv = more torque). I went for the lowest they had available, ​a 149kv motor. I actually don't recommend it—get something in the ~300 range—because this will easily yank the board out from under your feet.

You're also going to need an ESC to run the brushless motor; I got ​mine from Hobbywing (no, that's not a typo. Hobbywing != Hobbyking). Don't worry, I'll go over how you figure out the correct values, etc. in a later post.

I really dig these ​Turnigy "Long" LiPo batteries. They may be a bit too long to fit between the wheels on a cheapo $20 deck, but there's plenty of space on any longboard, and it allows for great ground clearance. 

The rest of the components you probably have lying around: you'll need an Arduino or similar microcontroller and some kind of remote control option. A Wii Nunchuck works great for this, and ​XenonJohn's tutorial is probably the best explanation for how to get started with it.

Assembly details coming up!