The used wheel economy is a funny one.
Sellers want rid of them because they're no longer needed and they take up space. Usually they've spent $$$ on new wheels and want to recoup some of it. Buyers, OTOH, want a particular spec / finish / tire which rarely matches exactly what the seller is selling. Plus they feel they're buying something used so the price should reflect that. And shipping is expensive, so unless the sale is local there's considerable added cost for either buyer or seller.
Case in point: My 968 came with 18" Carrera III wheels off of a 997, with brand new tires. I went back to the correct 17" Cup 1 setup (replicas, incidentally, albeit good ones from Mille Miglia. Snagged them for $50 for the set of four - well worth the eight hour round trip to pick them up from a seller who didn't want to ship. But I digress). If you believe opinions on the forums, my unwanted 18s were "worth" at least $2k, if not 3. But there in my garage they sat, taking up space, until a nice guy drove down from Jersey and picked them up for $750 cash. Which I was delighted with, since they didn't really owe me anything.
YMMV, of course. But as Borski says if you really want to sell these you need to get real. Your last asking price was $5k, btw, on 7/26.