Can I sell my iPod for what its really worth?

Correct me if Im wrong, but Ive done this and I assume its legal for me to buy CDs from a music store, bring them home and rip them onto my iTunes, and then sell them back to the same store for a third of what I originally paid just so that store can sell it as a “used CD”

Whats the difference? The artists are not making any money off of the resell either way. I know if I could get an iPod loaded with 200 albums I would buy it (as long as the price was right)