We've got an older 125.  Good small welder duty cycle is rather short.  IIRC we paid less than $245 for a new one but that was probably over 10 years ago.  Nice thing is you can take it out with a small generator to do things.  I've welded some pretty thick stuff with one just takes several passes but really 1/8" is going to be max and time consuming.  I wouldn't pay much over $100-$150 for that one.  Being a pawn shop that isn't going to happen though.