There was a time, not long ago, when I would've said that anyone can list anything at any price on eBay. It doesn't mean it will sell. But it's because of idiots paying these prices that it's game over for a lot of us now, certainly for specific items. I'm still managing to build to a half decent budget but they are rider builds and I'm staying clear of the items that have been over inflated.
eBay still gives up some great deals if you're prepared to look, but it is getting much much harder.