When my boy was 12, he's now 14, he wanted a PC for Christmas. I got one from Dell for �500. He was really grateful that he was getting a PC and insisted that he didn't need anything else. He still got a few cheap fun things in a stocking.
The same christmas I realised that if I spent that on him, i had to spend the same on my girl who is a year older than him. So I gave her �500 in cash, which was what she wanted, to go to the sales after Christmas and buy clothes. In January she probably bought twice as much with the money as she could have in December.
I'm fortunate in as much as I can afford it but I don't spoil them.