I follow a lot of artists on Facebook. I follow artists elsewhere, too, but Facebook seems to be where I see the most posts from artists. One of the artists I follow is Danielle Gransaull. She's got a pretty distinctive art style, typically focused on cute pin-up/cheesecake renditions of characters. She's done sketch card work with most of the major card companies, including Cryptozoic, Upper Deck, 5finity, Breygent, and Perna Studios. She also does the convention circuit and sells art out of her webstore. Her comic hero roller derby illustrations are pretty popular, even inspiring cosplayers to dress up as the characters from her art. The bio on her site mentions some comic book and web comic work, but I'm not familiar with her stuff in those realms.
A while back, she announced on Facebook that she was doing 20 sketches for $20. I know a good deal when I see one, so I ordered a couple of sketches featuring the two main characters I collect, Princess Leia and Power Girl.
I recall the turnaround being pretty quick, and I spotted the Power Girl sketch in a Facebook post prior to shipment. These are both great renditions of the characters in her signature style, and I'm very happy with both of them. It's always nice to get a good piece of original art, and these turned out really well.
She also included a business card in the package, with her contact information. She usually has some art available for sale, and it seems like she is pretty open to taking on commissions.