I guess if you donate it then you should let it go.. but I wouldn't donate it if I wanted it and thought I'd have to buy it back to get it.. Just donate $10 to the guild and keep your quilt!
We also donate items for the benefit of our guild coffers, but if they don't sell at the show we get them back. Then we can donate them to whatever organization or tell them they can donate it to the one we've chosen.. but we get that choice. I like that better.