Depending on space you have and what type of machines you like you could likely get two decent working machines for $1200 (if you look at earlier SS or better EM titles). Or buy one decent Bally, William's (System 6 or 7) or Gottlieb system 80 for $650 to $900.

My suggestion however would be to look for a Williams System 11 machine. There are about 30 total system 11 titles and you can still find about 1/2 of those in the $800 to $1400 price range. To me System 11 machines are some of the best built machines ever made and with so many great titles over 1/2 my collection is system 11 games.