For that kind of money, the best DAP on the market (from an audiophile standpoint) is the Fiio X5, which is due out in just a few short weeks. The trick will be to find a dealer who's not price-gouging when it's released, but the SRP is $350 (note, that's dollars).
Also consider the aforementioned Fiio X3 (but X5 is substantially better), and also consider iBasso's DX50, which, with it's more expensive brother, the DX90, about to be released, will be sure to fall in price, and thus will be an absolute steal.
There are a couple of excellent X5 and DX50 threads here on Head-fi, should anyone require more information.
There will be dissenters, but, broadly-speaking, I would say Fiio X5 > iBasso DX50 > Fiio X3
Plenty more options if the budget can be stretched, but these are still damn-fine sounding players.
Edited by Mython - 3/29/14 at 6:16am