We're going to a boys 4yr birthday today! (My daughters "boyfriend" hehe) I just asked my daughter what he liked & she told me "Ben 10" I think alot of boys around that age like ben 10

I got him a large bouncy ball which is filled with water & has blue glitter inside so when you bounce it, it looks really cool It was $12 from Big W. DD was crazy about the pink one so I thought if she liked the ball a boy should aswell... only in blue of course LOL

Good luck, I hope you find something today.