Instead of buying individual brushes, you can also get a set of brushes to get a better deal!
These brushes work best on an iPad Pro with Apple Pencil, but will still work on an iPad Air with a different pressure sensitive stylus. The best way to ensure the brush will work with your iPad / stylus combination is to download and try the free brushes first :)
Paper Texture Brushes$11.00
Dream Lettering Brushes$9.50