Yep I have definitely seen a rise in pin prices. Not just on eBay but on pinball forums also. Honestly, there are a few prices being asked that are well over the top and others that just seem to take the piss. 5.5K for a Space Invaders comes to mind. Fair enough if these over valued pins are getting sold, many are relisted time and time again.
Private sellers are sometimes just small time dealers that follow the same shenanigans as "big" dealers. There's a private seller in NSW that pulls auctions before the 24 hour deadline - if the price is not right. Then the game is relisted due to "non paying bidder" or similar. The dealer games listed at stupid prices is simply an auction used for advertising purposes only - to snare unsuspecting buyers. The games are not even cleaned ! The problem with relisting machines for months on end is that the reputation suffers due to the inability to sell that stock.
Prices are creeping up because demand is rising again. It is like a "second wave" of supply not meeting demand. The one thing I've noticed is that pinheads want more value for these increased prices.