There does seem to be some sanity returning to the eBay prices for WM. I've not been collating any data, but my impression is that common type blisters are now selling in the low to mid teens (£) from non-traders. That said, there are lots of traders who have slapped a £30+ price tag on common blisters and they just go round and round on 30-day listings.
I recently bought a pair of rock lobbers. One-off seller put them at £18 (incl. postage) on buy-it-now and I thought "at £9 each, why not?" and grabbed them for a future project. The traders were asking around £20 for single lobbers. No chance.