This is an interesting question, because you can’t necessarily donate them to Goodwill with last year’s blue jeans! Have you thought about keeping the bottoms and selling the tops? (I make this suggestion because I doubt anyone will buy the used bottoms.) Or, you could mix and match between outfits to create “new” ensembles. As for the one-piece attire, perhaps you could keep them and rotate your wardrobe so that clients don’t see you frequently in the same outfit.
I have seen online where people have dry cleaned the whole ensemble and sold them online. You can occassionally also find just the tops for sale on Ebay that have been “gently worn” so there is obviously a market. For myself, I just keep everything and pull it out later as a “new” outfit.
I like to keep everything, like workit4me does. I store them in the back of the closet and after a while I wear them again. My weight stays just about the same so wearing the outfits after a few months isn’t a problem.
You could also check out the market for buyers of used clothes! I mean those especially wanting models old outifts, washed or not! I’m not sure where you’d locate fetishists interested in this but I bet they are out there.
bellisimo is right on the money with her suggestion. I know a couple of people who make a good return selling their used outfits, shoes and even props, (ummm, don’t ask!) In this day and age there’s a buyer for just about anything.