I'd say buy an off the peg bike for that price rather than building one. Do you have the tools and know how to build a bike? And you can almost definitely bump that $500 up 'cause it never seems to cost what you think it will. I built a new bike over the winter and while it was an awesome experience and I actually saved a ton of money over buying stuff from an LBS(I shop the internet), I kinda wish I would have just bought something complete and then changed out the components as needed or as I could afford to. I love my bike now, and it's exactly the way I want it, but it was a PITA for a few months and I always hated seeing it only partially finished. Just my .02.