my bike was recently stolen (who knows how, it was properly locked and everything), and i had the idea that i'd spend at least a part of my summer building up a fixed gear for myself. it would be partly for the function of having a bike up at school here next year, but largely for me having something fun to do with my summer. so my question is, how possible would it be for me to do it, getting ebay parts, etc from scratch? i have no bicycle-specific mechanical work, but i have done assorted work on cars, and i'd say i'm reasonably intelligent when it comes to things of that nature, but again, i have no idea what's in store since i haven't done any work of the kind. money isn't a huge issue, but i'd like it to not be terribly expensive or anything. mainly my question is whether or not it would be possible/enjoyable for me to try do this (of course with the forum's help at every turn )?
It is very possible and very enjoyable. If you are looking to do it cheaply however, I would not recommend doing it one part at a time from ebay. Your best bet is to find a donor bike in good condition and convert it. You can make yourself a great bike for very little money this way.
Welcome! Huerro covered the basics pretty well. Building a bike is not too terribly hard. I also came from a background of working on cars, and bikes are even easier to work on than cars.
My biggest caution involves the cost: building a bike from scratch can add up. My first build was my Cannondale singlespeed, and I started with the frame. By the time I was done, I was over $500. It's a great bike to ride, but it was way over my initial budget. If you start with a complete donor bike you can do it a lot more cheaply.
Do some reading and research and you'll find a lot of good info! The people here in C&V tend to be very helpful and friendly, too.