Agree, unless you are ok with a customer using the coupon on ANY item, it's best to just change the price to reflect the discount and make note of it in the listing. Or, use EtsyOnSale. I've also seen some people use a main photo for the item with "SALE" written across it. It's an easy way to make the statement (sure, this item won't make it to the front page, but honestly, that's a pretty slim chance anyways)