Not to get into the whole morality on that, but you can buy the Fluval Edge for $100-130 now. Lets say they take it back to Jacks and get store credit for $120. So instead of $80 cash they can spend wherever, now they are limited to Jacks credit of $120. Last time I looked at Jacks prices they were fairly high depending on what you wanted. For instance, right now they are listing an Emperor 400 filter on sale for $59.97 (
http://www.jackspets.com/pet_tips/SalePg2.html ). You can find it online for under $40 (Petsolutions, Aquariumguys, ThatFishPlace, etc).
So figure prices at Jacks are about 150% than prices elsewhere, I'd rather have the $80 in cash than be stuck with $120 at Jacks. I don't know what the price is at Jacks though (it may be higher than $120).
Just my 2 cents worth.