There is not a lot you can do. :( Like everyone else mentioned trying soaking the stamp in glycerin.
There is a lot of flipping going on over at Ebay right now. Most of those sellers have never stamped in their lives so they are just unloading everything for a quick sale.
Sadly, right now with so many out of work a lot of stampers are selling their stamp collections on Ebay. I have been looking for those listings. It is pretty easy to tell who they are by the way they use terms in their listings because they term things like we do over here. A flipper is like "This is my lot of stamps!" A stamper is like "This is my collection of PSX, CHF, SU, etc..."
If you look at the sellers home page you can see if they are selling craft supplies or a myriad of products not related to stamping. If it's myriad then they are probably not stampers.
I am not being negative about flippers. I have friends who flip. It's a viable business. It's cutthroat and vicious to. You can score some great deals if you know how to play their game.
wavejumper- Shhh about Goodwill. Don't be sharing thrift secrets, ROFL! I don't need the competition on bidding, lol. I am addicted to that site. I hardly buy art supplies from them.