I got 50-something wall decals during a sale. They were still a husky chunk o' change, but if you were to see my apartment, you'd know they were worth it.
The decals had no trouble sticking, unsticking, and resticking to my lumpy-paint walls. The only downside really is that my decals were all the same dimensions, but they weren't all cut uniformly, and some had fraying edges. Tiling the decals didn't produce flush arrangements, but #whatev.