Ugh. There was, famously, a pair of Elvis Presley king-sized underwear -- stained -- that came up for auction in 2012, causing much outrage among the fans. You can google that. I think the reserve price wasn't met.
As for Donald, there might be some billionaire who would hoard Trump DNA for some nefarious purpose. With Trump's mania for preserving his name and likeness, so that all future generations may contemplate his majesty, he must have at least thought of preserving his precious fluids. I won't live to see it, but in some far-off time Americans may be treated to Jurassic Island -- The Immortal Douche Canoe Experience. I'm picturing a man-made island, approximately over the spot that Mar-a-Lago now occupies (soon to be a few miles off the eastern U.S. coastline.) There, multiple Trump clones may compete for dominance. A Donald Eat Donald competition. Streaming on Disney.