I know, it's difficult, isn't it?
The only good thing I can say is that a couple of the icons I really wanted are very, very old ones, and so I guess there is no longer anyone receiving any money for them. I have two of them now - the Hagia Sophia Christ, and the Resurrection from the walls of a Church I can't bring to mind the name of. The other is a very particular icon of the Theotokos and Christ, and I'm not sure the age of it, but I'd really like that very exact one.
I wish I could find icons at thrift stores and such, but no one around here donates them apparently. Which too is good - I'm guessing folks then are more aware and respectful. Or else there are far fewer Orthodox here. I once saw a non-standard very western-looking almost-icon of the Virgin Mary in the Catholic thrift store, but they were treating it well and asking high dollar for it.
My general understanding is that it is perfectly acceptable (at least in the U.S.) to purchase copies of "historic" icons where the author and their immediate descendants have reposed. Most of the Orthodox churches that I have been to have copies of some of the most famous icons, so this is what has led me to the conclusion that this is an acceptable practice.
Correct me if I am wrong, but I believe the miraculous Hawaiian Myrrh Bearing Icon is actually a copy of a much older icon?