You don't need 15 new pins to make money. I have proof of that. I'd say to go for 10 classic arcades set on free play and 4 solid 2K-5K pins set on at least 50 cents, and you will be set. If you can't work on the pins, you will need to befriend someone local to help you work on them for less than the "going rate". I charge around $50/hr. to local friends (which is considered VERY reasonable).

Also, creating an 80's "mood and atmosphere" is also LOT more important than you think, to try and maximize customers visiting more than once.

The problem with your idea:

You will not make enough $ to support your family with this alone. In other words, it is a labor of love, not of profit. If you're ok with that, I'd say to go for it.