I just bought a second hand JDS O2 + ODAC locally for less than $100 (less than $80, actually) that is in mint condition, and it must be one of the best deals I have ever scored. This thing is amazingly good. Another thing that attracts me is the fact that if some component should break it should be easy to fix, since the OPAMPS are socketed and the rest of the components are soldered through the PCB.
JDS Labs doesn't manufacture these anymore, but in the states you can still get them from Mayflower Electronics, though the price for a new unit is around $240.