We saw the same pricing pattern with the SkiData boards. Sell them cheap at first, then the next batch were $10 Euros more expensive, then another batch $10 Euros more...
It's just eBay price optimization, but I agree it sucks. Trouble is, once the prices go high, they rarely drop.
The exact same TG3 I bought for $50 (plus shipping) is now $85, so the seller must be getting some nibbles to keep them at that level. I talked to him when I picked up the keyboard (he's local to Virginia) he said he'd just heard about GH, wasn't aware there was this much demand for surplus mechanical boards.