I received a 15% coupon from Guitar Center.
The discount was good only on list prices and non-sale items. Well that sucks.
Anyway, I thought maybe I'll use it to buy an item that's seldom discounted such as Neumann microphones, Omnisphere, something like that.
Every item I mentioned to the sales clerk was exempt from this coupon; I mentionmed about ten companies and the coupon was not accepted by any of them.
Finally, I found one item where I could use the coupon. Guitar strings.
My price (list price) with my discount $12
The same guitar strings are on sale right now for $4