MrSaLTy, thanks a ton for this post - I made a stirplate nearly identical, and it works quite well! It'll spin a one pint starter with ease using stir bars ranging from half an inch to 2 inches. I got most of the parts from www.jameco.com
I'd be willing to use the leftover parts to make another 5 or 6 stirplates and sell them at my eBay store for around $30 or $40 (shipping included - that's only about $5 for my time). Additions would include an LED indicator and a power connector rather than the soldered/taped wires sticking out. I'm not looking to make a profit from fellow homebrewers - I just had a lot of fun with this project, and I'd like to share the results. Is anyone interested?