Not only does the money factor in, but the frequency at which you’re going to play it help determine the depth/replayability you may need.

I put a ST Pro at my parents’ house. I play it about every 2 weeks. But when I go play it, I can play for over an hour and never get bored with it. I may have been able to put an even shallower game there, maybe a system 11, and experience the same result. If I were there every day, I may get bored with it.

Find a wide range of games you like, and find something you don’t think you’ll get bored with given how much you might play it and what you can afford.