I usually buy any pin that comes my way.. that is stumble across by accident   i acquired nearly ALL of my machines that way and some (or most) of them aren't particularly sought after titles.

If the game has sentimental value, ie if you played it in your youth as an example, if thats the case then i say go for it! Most of my most recent purchases fall into that category, sentimental attachment to a particular title.

As i just said in another thread, you have to ask yourself "how much do i love this game and how bad do i want it restored??"