"Ebay was, earlier on, a lot like Gumtree is now, in so much as it was a great place to sell off unwanted items around the house..."

And still is - if you're selling second-hand items, eBay pretty much still works better than the alternatives (Gumtree, Facebook, etc). 

If you're selling brand-new items (and especially higher dollar ones), yes, eBay's pretty much gone to **bleep** with the entry of bigger players, and the now-obligatory Chinese dump-and-run merchants..