I believe those rebates are useable by bearer despite having been mailed to a particular person. If so, why not offer them for sale at a 50% discount or some other attractive and agreeable number? At least you would get something out of them.
I think I would rather give them to a forum member next time. It's not that much money and I can't use them. Call it a small gesture for all the selfless help fellow forum members give here.