My son was sent an 8 pack and a 3 pack of a new collectable for boys called Scatter Brainz:
They are highly designed to appeal to boys and make their mums go yuck as they are little darts with sticky brains that you throw at a target (apparently they can leave marks if thrown at painted walls):
With 64 in the collection they are also designed to be swapped with your friends. There is a handy chart on the back of the target to tick them off:
The initial pack comes at about £9.99 which would be a stand alone set. You can also buy a mental storage case for approximately £19.99 or a bazooka launcher for £14.99.
My children enjoyed throwing the darts with their friends and checking out the characters on them. For us the 11 darts are enough but I'm sure that many boys would want to add to their collection and my son may well do as he gets older. They are new on the market at the minute so not all of them are available everywhere yet.