I really don't know enough about the used MD market to comment, but $160 for a used and very old model MD deck doesn't sound too good to me.
You'll probably find around here that overall MD recorders are not held in very high esteem. Mainly because they cannot record uncompressed audio and instead only record audio through the ATRAC compression algorithm that tosses aside 4/5 of the audio data in order to save on how much data needs to be captured.
As several have pointed out, you might want to consider the Creative Labs Nomad Jukebox 3 -- aka the JB3. This is marketed as an mp3 jukebox (so you can certainly use it as a "bad ass walkman"). But it also records in .wav format, the same format used with CDRs, which does not suffer from compression algorithms. It also can record via microphone in, analog line in, and digital in. Bottom line is, the JB3 is comparable to DAT and far superior in almost all respects over MD.
So without knowing why you only seem to want a MD and not a JB3 or DAT deck (eg, the Sony D8 that was mentioned), it is hard to comment on whether you'd want to jump on the R50 MD for $160. Which by the way is far more than you'd pay for a used JB3. If you can find them on ebay, Creative is often selling them directly, new for about $140.