Depends on what the trombone is? We had a pile in our instrument room that one music store told us were completely unrepairable. Hillje Music began doing business with us and their brass repairman is a magician! I ended up going from no working triggers, to having a nice stock of quality trigger trombones to use. (Cost me much less than buying new ones) Terry, their technician, often is able to machine parts if they're not available anymore. Might be worth a second opinion on them?

Otherwise remember instruments are district inventory and your district has protocols/policies in place for disposal. Speak with your business office. You might be able to trade for scrap value to Second Hand Band or something? I have about 70 trombones sitting in our junior high instrument room that I need to do something with at some point. For some reason our district has practically collected them over the years!