My personal position would be to buy a relatively cheap DAC in the first place and have it upgraded with better components. I think this will produce better value for money, getting better components for less money. For instance,
Burson opamps are reckoned to be one of the best opamps you can get, I don't know of any brand name DAC's that install them, but I bet you'd have to pay a fair bit for such a DAC. You can get a Cambridge Audio DacMagic for £230, spend about £150-£200 getting Burson's fitted and few better capacitors and transform an already good DAC into a different beast. The only area I'd say that the upgrade path is hampered by buying a cheaper DAC to upgrade, is the power supply, DAC's from the likes of Cyrus would incorporate a far better power supply which is difficult to replicate in something like a DacMagic. Having said that, opamps, like analogue cables, can transform the way a DAC will sound. I'm not sure which would give the greatest benefits, a DAC with an excellent power supply and good opamps, or a DacMagic with an OK power supply (can be modded to an extent) and excellent opamps.
As you're giving a $ sign in your value, I assume your not in the UK, so you'd need to find a company that offers upgrades of this sort wherever you maybe in the world. I've spent a total of about
£650 on my DacMagic, I'd love to compare it to something like a Cyrus DAC X or even DAC XP, I suspect it would beat the DAC X.