Anything will sell if priced right. When I sell stuff I usually lower the price if there is no serious interest after several days. It's tough to realize that a mod is worth half of what I paid, even though it's like-new. The used market can be brutally unpredictable.
$300 will buy a lot of Coppervape mods, so you may be right about the "cheap" mods.
Good luck with your sale