Good place to buy/sell used audio I/O cards?

I want to buy a good audio card for my computer so that I can convert my old vinyl records to CD. Anyplace to buy/sell these so that I can get a better one than if I just bought new(lower cost to buy or to be able to sell after I finish recording)?
Any suggestions on which PCI card to use(Don't care about playback quality or multi-channel as I will only be playing back thru my CD player)?