DS1 (3yo) is getting a bit spoiled (thinks he gets a toy whenever we go out; yes, I do know this is my own fault). For example, I bought him a Bob the Builder truck thing he wanted last friday (it was on sale and he wanted it), although I did try to steer him towards something else (which was about £6). This am, he said,'are we going to the shops, Mom?' and when I said yes, he said, 'maybe I could get that other toy.' I explained gently that we would have to wait, etc.. but he started having a massive tantrum. (I haven't given in, BTW)
We thought one way of getting him to understand the value of money would be to start giving him a couple of quid a week and letting him spend it or save it for something as he likes.