DD11 goes to a specialist school for children with learning needs. She has 3 close friends, two girls and a boy.
The two girls openly talk about the things they're into and my daughter mentions things they like in passing. So I got them gifts based on their interests.
The boy doesn't talk about his interests. I spoke to his mum and she's said they also struggled for ideas of what to get him for his birthday. Based on this (lack) of information, I've decided to get him a wallet and put some cash in it so that his gift matches the value of the girls.
DH thinks this is unfair because the girls had two gifts and DDs friend won't have as much to unwrap. I think that as long as the value is equal then it's fine because nobody wants to be gifted stuff they're not actually interested in.
YABU - I should get him two gifts to unwrap so he has the same as the girls (gift suggestions welcome)
YANBU - Money is perfectly appropriate