The 680zx was one of the signature NAK models of the late 1970s and had a great reputation for life-like recording and play back. I have not personally used this deck but from what I've learnt from internet reading, this deck is up there with the best NAKs. However from a buyer perspective, the 1970s were a long way away and the condition it is in currently, is critical for your purchase decision. NAKs are complex machines and are difficult to fix. Run a thorough check on all the functionality and also listen to it for atleast 2 hours (2 fully C60 tapes). Also make some good recordings (if you can make a live recording, nothing like it). Bias calibration is also key to performance, so is the condition of the heads, pinch rollers, rubber intermediates, belts and of course, the motor and servo electronics. Also I've heard that the tape speed control can give trouble and get your deck to run at incorrect speeds. So check that out as well. Price wise, not sure if I can comment without seeing the actual deck, however I would believe that 8k is a bit on the high side for it, since its from the 70s and its by no way, a NAK 1000, CR7, RX505 or Dragon