Some of my favorite places to buy art online are the following:
1. etsy.com. Etsy is one of my favorite websites for art, accessories, and even furniture! Its a great site that puts you in direct contact with small business owners.
2. art.com has some of the biggest selection of artwork and at good prices.
3. society6.com. Society 6 is a community of great artists who sell originals and prints, perfect for any home looking for unique pieces!
4. minted.com is alot like art.com and society6.com where there is an artist community selling a wide variety of work.
5. 20x200.com which has a wide variety of art at an affordable price.
6. EyesonWalls.com which hosts a great range of limited artworks.
7. Artfullywalls.com has some great affordable pieces of artwork.
8. Purephoto.com has some amazing photography.
9. ugallery.com is great if you are in the market for a custom piece of artwork.
Bonus: One of my personal favorites to shop at is urbanoutfitters.com (and sister company anthropologie.com). Both Urban Outfitters and Anthropologie might be better know for their clothing, but they have developed a really great apartment home section and it has some really great and unique art finds there! As well as some of my favorite artists works. I also love Restoration Hardwares baby & child department for their adorable watercolors and animal artwork for nurseries.