Well, you could try the Audio Mirror DAC. That way you could get something that's almost exactly the same as the DAC AH, but pay a lot more. Then you wouldn't have to worry about having bought something cheap.
But seriously, there are loads of DACS in that price range (and a little higher).
The Lite DAC 60 gets lots of press as a giant killer. I think you can get them for around $460. You could probably pick up a used ACK! dACK! v.2 for around $500 (maybe a little more). A used ACK v.1 would probably go for around $300-$350. The new CI Audio VDA-2 is around $650, I think. It's meant to be really nice, but a little beyond your price range. But the now discontinued VDA-1 is probably cheap on the second hand market.
There are a heap of NOS DACS that popped up: the ACK, the DAC AH, the audio mirror, a couple of different ones from Scott Nixon, plus a couple of DIY options like the Monica II. They will all have a similar sound: preferences between them will vary.
Also, you might be able to find a used ART DI/O with modifications. The Mensa mods by the Bolder Cable Company were well regarded, and you might find a Mensa DI/O on audiogon for $350-ish.
If I were buying new in your price range, I'd probably try the Lite DAC 60. Unless I could stretch the budget a little and try the Channel Islands VDA-2.
Chad