The twin puffy stickers are some of the hardest to find, as you know, but they dont tend to be as expensive as some of the more sought after stickers. Not sure why.
But I would still think £15-16 for one on original backing however. I think I paid a few £ more than that for each of mine but I am an overpayer
Most of the lollipop, sundae, ice cream barrettes will sit from £4-6 depending on which ones