I like what you're doing...and it's a refreshing and innovative approach: an intermediate way of attracting the general public's (or at least the neighborhood's) attention to pinball in a positive manner. This is much better than hoarding pins in your basement that few people get to play. The public can occasionally play your machines, even if not in a true public location.
However, I don't think you'll be able to convert many people into pinball hobbyists.
There are plenty of people who enjoy pinball that are not hobbyists; some are new players that have just discovered it, and some have played for many years. In our league here in town of about 20, I am one of four members that actually own machines. And two of the four that do only have a single machine, with one other having two machines. Most of our leaguers have no interest in owning a machine; it's not for everyone, for various reasons.
I still believe the best way to spread pinball to the public is to operate. Even if you only operate a single machine, in the right location (that Pizza Hut?), it will draw a lot of interest...people will be talking about it, especially if pinball has been absent for a while. I know it's not practical for everyone to do so, but if you are able to, give it a try. You will be surprised by the thanks you will receive from random local people, many you would have never met in a league or at a show. And, you might just generate a little cash flow on the side. You don't have to have a brand new Stern LE or Medieval Madness...a Rollergames, Bride of Pinbot, or Dr. Dude will do.
-Mark