One seller whose shop I like to peek in on from time to time is pengcath. Although I haven't actually made a purchase from this shop yet, it's on my list of things to do.
Her shop has lots and lots of really cute illustrations, water colors, cards and stickers. Her work has tons of charm and is executed with a whimsy that isn't sickeningly sweet. Most impressive are the cats. This is a woman who gets cats and it shows in her art. Her work is very expressive and you can see the personality of her subject come through. I can only image the wonderment that would be aroused by actually having a piece of her work.
She's got a wide variety of products to appeal to all sorts. So what are you waiting for? Go check it out. She is found online and in B&M stores all over. For all the information you need to find her work, visit her site at cathypeng.com.