What you say about GS is interesting, selling vintage glass and even when searching for the same I've found it useful. But even though they have quite a lot of modern items, some from High St. shops near me, I've never used it to buy new stuff or even compare prices.
Not so good if someone is selling new items on ebid, but better if selling the sort of Collectables that Ebid seems to have a lot of, especially if sellers take the trouble to get their items seen there.