If you happen to live by a Michaels and you happen to spend some time in their clearance aisle, make sure to grab some of their chalkboard stickers! I got a pack of clouds for 79 cents and I’ve heard (through the internet) that there are lots of other shapes you can get.
They sat at my house for a little while until I got some Crayola Chalk which looks so bright and fun against the black. The only thing I should say is that these are chalkboard stickers and not removable chalkboard stickers. I stuck one on my fridge, tried to move it, and it didn’t really come off in one piece.