For the next two weeks, my LYS is buying unwanted stash yarn for a dollar (in store credit) a pound. I'm viewing this as a swap, which is allowed under my stash reduction plan. I've really wanted to knit Wicked; maybe I'll spend my credit on some CP Kid Merino for the mohair version.
That is a lovely sweater. Have you weighed the stash you plan to trade? I think I'm going to bag up my trade-in stash, stand on the bathroom scale, and do the math to get an estimate.