How much do you spend on birthday gifts?

When your kid gets invited to a birthday party of one of her preschool
classmates, how much do you spend on the gift? Please be honest :)

I spend around $10. I ask what he/she would like and buy whatever I
get for $10. I don't like giving or receiving expensive gifts. If your
kid receives a cheaper gift would you be offended? Also, if you have
more than one kid that attends the party, do you send two gifts or
double the price of one gift?

Thanks.