The big issue with EM's or even cheaper SS machines is "the math". If you buy a "fair condition" EM for near market value and toss a $200 backglass into it or even a $50 set of nicer legs (or coin door) you can get upside down very quickly.
So using this machine as an example - you buy it for $550 but are not happy with a couple damaged plastics, condition of legs and the backglass. Next thing you know you find a nice backglass for $150 "I have to grab that" and a good set of used legs for $40 "how can I pass those up" and then toss a new set of rubber rings, a few bulbs and replace a couple other minor parts and next thing you know you have $800 to $900 in a $650 machine.
When buying machines under $1000 it is very important for the condition to be something you can live with or realize just how fast you can get into a machine "too deep".
So keeping it simple - your best bet is find something with at least a nice backglass & playfield, decent coin door, plastics, etc. That way a "cheap machine" doesn't become an expensive machine. There are plenty of "nice" EM's for sale under $750 if you take you time and find the right one.
The other thing - once you find something you think you will like - at least pull up videos of people playing that title and see if "flow" is something that looks good to you. If a machine looks nice - you enjoy the gameplay - and works 100% there are not many titles out their that are not worth $600 to $750 unless they are real dogs. The key is take you time and find the "right machine" for you.