I think this is another challenge for these kinds of stores. The market moves on and their inventory becomes obsolete. So you end up with a store full of BCD thumb wheels and tube sockets and wire wrap materials that very few people want to buy. They'll never recoup the investment in these things because they've become obsolete. Even more modern things have the same problem - if you bought a pile of Arduino Due-s or BASIC Stamps to sell good luck moving those today.