In the newest issue of Popsister there's a giveaway of beauty products and clothes sponsored by the new Essence machine.
The prizes aren't really purikura related, I guess just in the "beauty" sense! It also looks like you can only enter via QR code which, despite apps that promise otherwise, I haven't Bern able to get to work on the iPhone. I wait patiently.
Good luck if you are going to enter though!