I've returned a bunch of stuff in the past, both fish and corals that have outgrown my tank or been troublesome to other fish in the tank. For the most part u dont get anything close to what u paid for them, but in most of my cases the fish or coral was much larger than when i bought it so i get more for it because it was worth more when i gave it back. They always put it in one of their tanks and mark it up to about 3 times what they gave you for it however. I really don't mind though because i got something for it and its better than nothing and u got all that time to enjoy it while it was in your tank so in my book thats a win for me. Something about this hobby that u have to realize and accept is that there is no residual value on anything, livestock or equipment. You can't get half of what u payed for anything once you've put it in your tank.