What would be an appropriate gift for a 7 year old classmate?

My daughter is invited to a birthday party this Saturday for one of her classmates. The young girl will be turning 7.

We just moved to this town, so we don’t know the family very well. We are also very low on money right now, and to be honest, I’d like to avoid shopping tonight (night before Thanksgiving) and Friday (ugh).

Would it be ok to put a little money in a card? How much money would be appropriate if we did this?