If you use the discount link and a coupon, and they cancel the order, what happens to your coupon? Does it reemerge in your coupon bank or is it just gone because you already "used" it? Or hell, for that matter, what happens if you just use a coupon with the regular link and they happen to cancel it due to insufficient stock? What happens then?

if misused then its cancelled and gone forever.

due to insufficient stock, i suspect cancelled, but you can argue that they shouldnt cancel an order cos its not in stock. thing is, the way they work they only have back-stock by accident more than design, and their prices are a reflection of the buying power muscle they flex on getting a large initial batch or making large orders which they may not feel they need to restock once that titles no longer performing at a rate which warrants restock to the same initial extent.