Enough with all the hate for fixies. I just built myself a single geared fixie and it's mad fun. Being an engineer, I customized it beyond the norms to be a custom bike. If you want something cheap, find a garage sale, or you can buy a cheap schwinn road bike and then build from there. I would suggest a bianchi though, the super pista is insane, but pretty expensive as well.
check out harriscyclery.net for info on them as well