Can Ebay keep my head above water?

Okay folks I need some sound advice.... I have been selling on Ebay for almost a year now and really enjoy it.  The question is, as a small time seller (at the moment) do you think if I am prepared to put the time and money into it, Ebay could give me a slightly more comfortable lifestyle or is it only really achievable for the big shop sellers?

I seem to do okay most of the time selling new and used clothing and I like to think I know my market, I think if I put my mind to it I could probably sell twice as much.

I would be interested to hear your views and will appreciate any advice you can put my way.

Thanks kat