I sell stuff on eBay. It can be quite surprising what will sell and what won't. It can be time consuming to sell stuff on line as you have to take a picture, do some research to make sure you describe it well and list it at a good price, i.e., one that will sell while still making the effort worth your while. Plus, once it sells, there's the time it takes to wrap it up and ship it.
I do it in my spare time. If I have time I'll list stuff. And I just continue to relist till it sells or till I figure I've given it enough of a chance and I just ditch it. They give you 50 free listings per month, plus they often give out 100 or more free listings randomly. So I never pay to list, only if it sells.