So I'm looking to drop $500ish on a new bike. This will be my first "nice" bike, but I've been doing a lot of riding for the past 6 months, borrowing bikes from friends.

I am thinking about getting a single-speed flip flop because I want to be able to mess around riding fixed gear, they are mechanically simpler, and cheaper from what I can tell. I really have no idea what bikes i should be looking at though. The only decent single speed that my LBS had was an Origin-8 Uno for $550. It rode pretty nicely, but I had never heard of it.

I live in Louisiana, so I dont have to deal with snow or anything like that. I'll mainly be using the bike to ride around campus, haul ass for the 9ish mile ride to work, critical mass, and other fun rides.

Is a single speed the best bike for my case? What are some solid bikes that I should look into? How do I determine what size frame is best for me? I've had people tell me I should be a 58-60+ just based on my height...

Thanks