I think that this is probably the best idea (coupled with continuing to save), and I'll explain why.

I think that the "you'll own two within three months" phenomena is probably as pervasive as it is because we're trying to satisfy that initial "want" as quickly as possible--and we convince ourselves that any ol' machine within our price range will do. Only to find that that machine that we ran out and bought quickly is not the machine that we fell in love with (in this case the OP fell in love with Stern's Star Trek)

Chances are--he'll still buy that Stern Star Trek shortly after the initial newness of that impulse buy wears off. My advice would be to continue to save until you are able to afford that machine that caused you to fall in love. Why? Because you won't be able to avoid comparing Blackout or Wipe Out to it, which will only leave you disappointed. Consider waiting a bit longer to save up for that pin that you know for sure that you will love, because you might find yourself with buyers remorse if you don't.

I don't disagree with this, he may in fact find out after playing Star Trek for a while that he wants to sell it to purchase something different. That's certainly a possibility. I think that it's an even greater possibility that he purchases something within his immediate budget, and is left wanting more because he keeps comparing it to his first love, particularly since he said that he could save and have the funds that he needed in a couple months.

I'd second that, and add: "Use the Pin Map to try and find those games that you think you'll enjoy on location, and see if you really like them or not". I fell in love with the theme and video gameplay of several pins, only to be left indifferent after actually playing them on location. That aside, it sounds like you've found some games that you really enjoy. Now the real quest begins--finding that perfect balance of price, condition, and location/aka "I wish you were closer!". (I'm in the same boat as you man, saving, searching, and waiting--all the while playing on location when I can.)

I doubt you'll see anyone advocating going into debt for a pin. That aside, there is such a thing as a good use of credit, particularly if you are trying to build your current credit. Assuming that you have the funds to pay it off, you could use this as an opportunity to build your credit as well (rather than just walking in with a stack of greenbacks). I rarely purchase anything with cash. I save up the money until I can afford it, I'll purchase it with my AMEX, and then pay off the balance in full during my next billing cycle. That way I get the purchase protection, the rewards dollars, and continue to build my credit worthiness.