If they are removed carefully without busting the T&G, and you pull the nails out through the back (never pound them forward) or grind them off, listing them on Craig's List or in the local paper might be your best bet. If you don't want to risk taking them up, you could offer them in place for the buyer to remove. I've done so many times and rescued some beautiful antique hardwood flooring. It isn't rocket science but you have to think backwards of the way they were installed, go slow, and not just yank on nails. Get money upfront and non-refundable in the case of allowing someone else to do the removal of course.
There are companies that recycle old wood floors. You will have to search online to find one near you. I think you will do better with CL or something like it though. The ad will be free so why not give one a try and see what happens?