1. Etsy. Etsy is the mother lode of independent arts and crafts. While quite a bit of it skews towards the cutesy or granola, it's still a treasure trove of original art work. What's more, the vast majority of art on Etsy is extremely affordable (i.e., under $50) and while many of the pieces found there are smaller in scale, the price makes it easy to pick up two or three (or four) of your favorites that could easily be arranged together to make an impressive display. Some of my favorite artists include:
2. UGallery. UGallery is an online store dedicated to selling the work of art students across the country. I particularly like their search engines which allow you to browse by cost, size, medium, color and even the school the artist attends (just in case you want to support your alma mater, I suppose). The art on UGallery tends to be more expensive than the art on Etsy, but I think it's generally a better quality (and again, you're supporting art students) and you can often choose from a range of sizes for any particular work to suite your needs. I am particularly found of the work of these two photographers:
Obviously, art is a very subjective thing and what I find beautiful or interesting may not exactly tickle your fancy. In fact, it's pretty clear from the selection I've made here that I'm currently into photography (especially landscape photography) and what I suppose could be described as gothic surrealism. That being said, there are many, many more artists on all three sites who produce vastly different work in a variety of mediums (photography, collage, painting, drawing, etc.) so I encourage you to poke around yourself on each of these sites and see if you come up with something you love. If you find anything great, be sure to let me know.