We were recently sent some Orbeez. I don't know if you have seen them around but they are all the rage with my kids at the moment. They also love anything that comes in some kind of blind bag surprise form, they also love anything that they have to open by taking packaging off.
The Orbeez come in a globe form. They are filled with clear Orbeez so you cant see which figure you have in your globe. It works by taking the packaging off then unscrewing the top and pour a little bit of water in the top. As the water goes in the orbezz become more invisible and show which creature you have.
They are great pocket money treats and my two loved them. You can play with the toy over and over again as long as you keep the orbeez sealed they should last a while. My kids took them out and make potions and other things with them. The orbeez cost £5.99 which are a lot cheaper than other pocket money on the market. They will also make perfect stocking fillers at Christmas too.