I've always thought my DC (8 & 10 yo) don't do that many outside things but we spend:
Cubs/Scouts (weekly) £15pm each
Swimming club £18pm each
Wildlife rangers (monthly) £3 each
Tri-club (weekly) £8pm each
So, that's £88 per month, between them, out of the household expenditure.
Neither are particular keen on ball sports, so the swimming and tri are pretty much their only exercise (although active in other ways at scouts etc too)
They'd both like to join a children's club at the climbing wall, but that's another £88pm between them. It's not that we couldn't afford it, but £90 pm does make a difference to us and I'm balking at the total cost of their activities. At the same time, I do like to know they're being active and social and I guess talented sports or musical children cost their parents more?!