If you're even marginally aware of design blogs, you probably already know all about Jamie Meares's store Furbish in Raleigh, NC.
Jamie's blog I Suwannee was one of the first I started reading ten or so years ago, and I never stopped. She has a great eye for mixing color and pattern in interiors, and I adore her aesthetic.
Furbish always has some art for sale, but I specifically wanted to call out their artist pop-ups, which are all online. As the name implies, they don't happen all the time; you have to follow Furbish to find out when they're coming, but it's so worth subscribing to the emails just to stay in the know about these pop-up sales. Jamie finds some really cool, eclectic artists for the sales, and if you share her cheerful, feminine aesthetic, chances are high you will be introduced to someone whose work you love. She keeps everything at pretty reasonable price point too--usually under $1,000, and often under $500.
The downside is that the sales are short and well hyped, so there's some pressure to purchase quickly. Pieces start to sell as soon as the sales go live, and some of their pop-ups sell out in the first day or two. I prefer to put a lot of thought into any art purchase, so I'm not generally a huge fan of situations that require a quick trigger pull. But like I said, they're advertised ahead of time, so you get an opportunity to research the artist to get a sense of the style and price range. They don't post a lot of specifics beforehand, but Furbish staff have always been quick to answer my email queries, so I think they'd be willing to give you a sense of the art size and price range, if it's not obvious from your independent research.
These pop-ups have all passed, but here are some examples to give you an idea of the kind of art to expect from Furbish: