The venture market of hopeful errors. As in any venture capital are risks of a blow-out, a zonk, a big nothing much. There are countless minor(very minimal) doubling and RPMs on coins of the new millennium(say 1996 on) but one has to be their own judge as to what eventual profit. Personally, none for me. The time, space and capital is better spent elsewhere in the current miserable fare of the US Mutt! The current rise of interest in error coins IMHO is nothing more than a passing fad. Playing on the human propensity to get something for nothing, this usually ends in rapid disappointment and complete disinterest in numismatics afterward. The "rewards" are really just not there. There is no "real" market for minor errors, a slight one now, but dwindling as the OP has noted himself, and is now questioning the decision. To keep 5000 is probably not wise. A few hundred, stored correctly in twenty years may see a profit, (check greyshet on 1980's stinkin zincolns) but the rush for them newfangled designs, too many have jumped on that wagon, in twenty the market will be way over saturated, meaning a very low rate of return. I'd opt for other areas.