in my opinion, you should either buy complete(sst, kilo, madison- they're all fine choices. madison's the best but it's also the most expensive) unless you don't need the bike for a while and are happy to look at it unfinished.

they're no sense spending five dollars to get a crappy part on the bike if you can wait to buy the 25 dollar part you really want.

trust me. having a parts bike full of parts i bought because i needed a part and couldn't afford the expensive part i really wanted has made me very discouraged on building a bike that doesn't cost a crap ton of money.

just buy complete for 500. you'll end up with a nicer bike for less work.