You need to use some common sense if they only have a few don't do it. I always choose items that multiple shops had loads of sock of like different brand of tampons and sold to a county that had expensive tampons in conparison.

It's a great way to try new stock out before buying, if you must, I try to keep it simple, low risk, like selling stuff around $5 for $10 but in volume.

If you put something into a 3 day auction get the store to hold it back for you go back buy it post it.

You really do though need to use common sense and look at your personal situation. Try 1 or 2 out see how it works for you.

Philip