Using the results from your initial search you can locate the most popular sites on the net for buying art online. The most popular doesn't necessarily mean the best but it does indicate that the site is well established and has been visited by many customers which in turn indicates that it has some merit.

Of course one of the most obvious places to start looking for art is eBay. eBay has revolutionised home shopping and is essentially a giant market place where people gather to sell absolutely anything and everything old and new. Artwork is no exception; up and coming artists are given the opportunity to advertise their work on the site and not only make a little money but gain some much needed publicity and attention for their work. A search for art on eBay gives the following results:

Paintings (9112)
Posters (7359)
Self-Representing Artists (5863)
Folk Art (2635)
Photographic Images (1661)
Sculpture, Carvings (1354)
Other Art (902)
Digital Art (609)
Drawings (548)

So as you can see there's no shortage of art available. While some of it will be for sale by the artist him/herself other pieces will be second hand that may have been in the possession of many others before you. As eBay works like an auction if you are especially keen to acquire a particular piece and money is not an object then you will have the opportunity to bid against other interested parties. Enjoy the experience and imagine you are at Sotheby's bidding to buy a Picasso or a Renoir!