You can do it. I scavenged a 62cm Schwinn Traveller frame from the 70's and fixed it up entirely by my own hand. I've never worked in a shop or been taught how to work on bikes, I've just been fiddling, reading and asking my friends for years. I repacked the headset, replaced the bottom bracket, put on a new wheelset including a front wheel hand built by me, put on new saddle and bars, fiddled with ratios and chainline, and now I have a hunky-dory solid-as-hell fixie. The whole project cost me around $225. That said, I am a pretty serious dumpster diver so I got everything except wheels, bars, tires and tubes for free, but you get the idea.