There are no fees for sales on gumtree (well not for anything I have sold). There are no fees to list either unless you want to pay for extras like more prominent positioning of your add at the top of the page etc etc.
I've bought and sold numerous stuff on gumtree (not pins tho) and never paid a cent, it's great for sales of stuff that is too hard to package and ship, or would cost too much to post relative to the value of the item.
I actually watch gumtree for pins and don't even bother looking at eBay.
