The Sony 7700's are getting long in the tooth (5 - 9 years old now). A friend tells of shelves of them at his shop, all broken. Look for small green tag on the back. It will give year and batch. I had one of the last, a 01B. The 7700 has both CD and DVD heads which made it unique and quite good. Empirical Audio still mods them I believe, but you could be looking at $2000 with a decent DAC.
The $150 Oppo 970 is the current low cost darling, but I don't know of cheap mods (RAM's start at $640).