I think you're going to be hard pressed to find anything noticeably better in that budget.
You could probably find a used Specialized Langster Pro, Felt Tk2/3 Bianchi, Cinelli, Fuji, or a Planet-X/Stradelli/re-branded carbon, but I'm not sure how much, if any, difference you'll notice, other than a better paint job. (Of all those, I'd probably opt for the Langster Pro.)
That said, given your stated interests, I'd suggest you look for a Dixie Flyer BTB, but again, I don't you'll find one in your budget.