A lot really depends on how deep you want to get into the repair /maintenance side of the hobby, unfortunately the old saying,"if it ain't broke, it ain't pinball" is largely true, especially on older machines. Unless you are buying a System 11/WPC era game that has been completely gone thru both mechanically and electronically, you can expect some issues which if you're not prepared for, could make for a less than happy first experience.

One of the best things about getting into the pinball hobby now is how much info and parts are out there, it truly has never been easier to find what you need.

I would look closely at the Taxi, it is a fun game and the price sounds quite reasonable in today's market. System 11's are generally quite solid, so it, Whirlwind or F-14 would be good first choices within your budget.

Good Luck!