I am quickly going to add my 5 cents here.
I used to send a gift EVERY TIME I received an "invite to a party at school" - I did it religiously. My son's birthday swung around at the end of the year, and I threw a party at school as I was also throwing a seperate party at home, with cousins and other friends not at teh school.
Less than half the parents sent gifts.
I took it to be either my kid was severely slighted, or that I had misunderstood how it worked and that the feeling is not to send gifts.
I decided to stop sending gifts to school for kids parties at school - if there are 25 kids in a class, that is about R60.00 - R120.00 a gift and gets totally out of hand.
I then thought, okay I will only buy for the boys when it is their party for my son, and for the girls when it was my daughter.
But again I found kids I religiously bought gifts for did not buy for my daughter when it was her birthday.
So again I took it to be the "sign!"
Right now I buy gifts for parties that my kids go to - outside of school, and that is pretty much it. If I throw a party at school then I 'expect' no one to buy a present.
But I agree, I am not sure of what the message is if a school party is held at school you one gets an invitation .... because I sense it as a "hey kids birthday coming up, there will be cake, send a gift..." but until I am super rich again, I am opting out of sending gifts as indiscrimantly as I used to.