Quoted from Gatecrasher:eBay is by far #1 for selling just about anything. When you put a pinball machine on eBay it has the potential of being exposed to over 30 million people. No other setting comes close to that.
Craigslist is OK but far fewer people will see it.
Pinside and RGP are both good for pins because of the obvious.
Is there an option for the buyer to set up the shipping arrangements on ebay? That seems like the big drawback of ebay if not.