Mel,
Some of us sell our retired sets at stamp camps for a nice discounted price to customers, or have a 'stamping garage sale' of sorts during classes or camps. Sometimes, retired sets are found for sale or trade right here on SCS. Some sets just never leave their original home, since they're loved for personal use! The $$ you get by selling them when they retire, can quickly turn into new stamp sets!! The retiring sets give way to new favorites pretty quickly ... look how everyone is dancing over the new ones now!
Smiles to you!
TexasGrammy