I have been involved with machine tools all of my life. Here is my advice...
1. Look for an older unit, they are better built! For example the bridgeport mills from the 1940's will outlast a brand new one. Most of the mills made after the 1970's went to a thin wall casting, that made the machine lighter than before. They are susceptible to chatter in the piece, due to not being able to absorb the vibration.
2. Old Chinese machine are junk. They quality of the castings are not good. The materials they are made of are cheap. If you find an old (1980 or earlier) Chinese mill or lathe I will almost guarantee they will need to be reworked. The ways are most likely shot. On the other hand the newer Chinese stuff is as good as anything else being produced.
3. Go find an old Southbend or Lablond lathe, and an old bridgeport mill. Then spend a couple of bucks to have my dad check it out. He will be able to tell you if it is worth anything. Just because someone threw a coat of paint on it does not mean the machine will hold tolerance.
Good luck