Etsy and DeviantArt are good sites for selling artwork.
I also agree that small local places might be a good idea for her too. Around here I've seen local artists selling their work in places like wineries, small galleries, coffee shops, and locally owned bookstores.
Also, if she wants business cards, have her check out moo.com. You can get their mini moo cards, which are adorable little business cards, printed with your own images on the front and your contact info/website URL on the back. They run deals all the time where you can get a box of their mini cards just for the $5 in shipping. They're totally worth it. I have 3 boxes of their mini cards. They're a big hit with people cause of the small size. She should have some cards printed up with her artwork, and keep them with her to give to people who ask about her art.