Here's an out there thought....And maybe already mentioned...I have no clue what shipping is on a machine. But how about a raffle on a couple machines? Doesn't matter condition, even if they are project machines, what era, etc.... I'm not sure if the interest would be there or not though. But I look at it this way, Your wanting to reach as many people as you can that may not have deep pockets. But most any one would kick $30 or $40 towards a raffle ticket. If the numbers work out? a percentage gets donated to pinside, pays for shipping, and maybe would even be a mystery machine and mystery condition. I'd take the chance! I'd bet others would too. You may even make more that way on a few while just shipping them off. No waiting, money's already in hand, etc...You would have to play with numbers a little and based on your pm and thread interest, would probably be a good indicator of possible ticket sales etc...
You could even do good machines. Not sure how you would do that to protect your end if there weren't enough ticket sales. But a few machines may even get you way way more than you wanted and someone would get one heck of a deal! By reading your threads I would feel your honest enough to do a random drawing. The cheaper machines would be better though. I, or maybe a bunch of us would be thrilled to get any kind of project on a $20 to $40 chance,or whatever amount works that covers you,shipping,a donation, based on the value of the machine . Maybe even some of the stuff that no one wants from the lists. You have one left at the end of the week? It goes up for the weeks raffle. or something, the idea would need tuned and played with....... Right now I have 3 huge projects so I shouldn't be talking! 2 of them should have been parted. But I'll save them and bring them back from the dead , slowly!!! So, maybe I'm in a small portion of the pinball community? I'm happy getting junk as long as it's somewhat all there, even though a couple I way over paid for were missing more than they are worth in the end, but I wanted them!!! I like working on them and seeing how far from the dead I can bring it back.
Just an out there thought. I know it doesn't solve your problem and something like this may even add more to it. Would be kind of a fun side thing though! Randomly pick the person from the raffle and randomly pick a machine from the price range would be fun too!