If you’re looking to more like, paint and smudge media all over a canvas from scratch than layer-effects post editing awesomeness, autodesk has a program called sketchbook pro. Might have a newer version out, I’ve got 6.2. I mean, it’s still got layers, but the focus is more on imitating real media than pic manipulation.
Got a nice trial that’s 14 ‘days’ (14 instances of clicking ‘run’ on the application, you can get months out of it if you aren’t the sort to turn your computer off), and it’s significantly cheaper than photoshop. Like, it was around 60$ for me instead of 600$. (Not disclosing whether or not I payed for photoshop or not, heh.)