Haggling—it’s not just for flea markets.
Don’t be afraid to ask for a discount on an item at a regular store, even if it’s already on sale. (In fact, I’d argue that’s the best time, and you’ll see why in a second.) Your typical department store expects to lose a certain percentage of inventory to damage. When a shirt loses a button or a box gets smushed, the item is put on clearance. Either it sells or is eventually sent to salvage.
Don’t be a jerk about it, and don’t act all affronted or entitled. Just ask. If you’ve found something that’s the last of its kind (this doesn’t work if there are more, because the manager will just tell you to get another if it bothers you) and is dirty or dinged, take it to customer service and ask for a discount. I find that “Hi, I’d like to buy this, but I was wondering if you could mark it down a little more because of the [insert flaw here]?” works almost all the time, with a savings of at least 10% (and once as much as 50%). I’ve done it at Goodwill and I’ve done it at Macy’s.
Any small embarrassment you might feel would likely be assuaged by the resultant lower pricetag. I do recommend holding off on the victory dance until you’re out of the store, though.