I would very much like a Gottlieb Stargate, I thought being a Gottlieb Premier would make it more affordable but it seems pretty on par with most of the other mid range DMDs.
I have worked as an arcade tech before so I can tell the condition for myself but deciding the value is the hard part. I also have not played too many different pins and having two young kids means pinball nights on the other side of town are out. There are no pinball dealers close by. I do want to try out some more if I can though.
Can anyone suggest some specific pinball groups on facebook?

You can't go wrong with a GTB SYS3 like Stargate. Awesome pinball. VERY reliable platform and parts readily available. FB groups - you need a "buy and Sell" group ?