Present for 3yo birthday party boy we don;t know very well?

[ToddlerYears]

DD's been invited to a birthday party by someone at her nursery. We don't really know them - just spoken to the Mum in the park and am friendly enough with her.

I'm reluctant to turn up at the party empty-handed, so was wondering what we could buy the little boy which would be inexpensive and disposable (as we don't want to add clutter to their flat).

Any suggestions please?

A kite

A book / book token

A t-shirt for spring / summer (Not many people but clothes for boys, ime)

A t-shirt is a nice idea. I have a three year old DS and that's something I would appreciate.
Or how about a money box? We've just got DS one and he's quite smitten with it.

Thanks. Will look into t shirt idea