I browse it from time to time but have never bought anything. Every once in a great while there may be something of value on ebay - mostly rare mods/atties, but since vaping is very much a social media/forum thing and communication between potential sellers and buyers mostly happens there, ebay isn't really offering anything above. I also think that group member vouching is more reliable than seller reviews for vaping gear.
This also means that a lot of vendors there may be suspect, but you can get a deal (very rarely), or at least get a lead to a shop, as said previously.