If I have leftover, I serve them re-heated
If I produce too much which generally happen during winter/ breeding season time as some animal go off feed, I euthanize the feeders and freeze them and than feed them to my females after they lay and resume feeding (female after laying are generally not picky and will eat F/T even if it is not what they are usually fed.)
If I had to sell them I would use Kijiji.com or place an ad on similar website or try to find local herpers that could need the surplus.