It's pretty fun. Looks simple, but I don't mind that in these types of games. Could do with some improvements here and there though.
For instance, make it possible to increase our stock size for money. Add more costly items, because as it is right now it's taking me forever to hit 10k. Some sort of system with actual customers would be nice, whether it's them disliking you for turning them down or liking you more for buying stuff from them?
Also, the most profit I've managed to make off the Dendy Classic is 1 dollar, no-one ever wants to go below 100 on that thing. The signed Super Mario World cart as well, never managed togo below 300 on it. Is this intentional?