Be forwarned! Taking any equipment to Sam Ash, or Guitar Center to sell, or trade-in is gonna be a very disheartening experience to say the least.
1st of all, you paid retail price!
2nd of all, they can get the same product at wholesale (or whatever arrangement they have with the manufacturer)
3rd of all, they offer you half of what it would cost them to purchase the product. So you can excpect to get at best a third of what you paid for the set, or per drum.
It's understandable, and the way of commerce, to buy low and sell high (and I don't mean altered states

).
I've exerienced this before, and will only do this again in a very, very desperate situation.....like if a bill needs paying, need food, or...well, you get the picture. Wife finding out about an unapproved purchase, may very well qualify however!
Good luck and hopefully, you'll walk away with a good deal none the less!
Stay well!
Onile!