Spend whatever you think is right. Invest time in getting the right bike. Since you said "citibike," safe guess you're in NYC. Where you gonna keep it? Make that easy on yourself if you can. Where you gonna ride it? buy for that, like not a tri bike or super aero. Who's gonna service? Find an LBS you like, even if you're a handy mechanic, and make sure they're available for the tough stuff (not much, but...). For instance, if I was still living in 11231 (not anymore), I'd have a very light endurance bike that's easy to carry up the stairs, not very high-end wheels due to road quality (ugh), it would live in the apartment hanging on the wall (WAF issue to be sure), and I'd put good lights on it. Gotta think holistically.