Ymmmm
Sell cookie dough.
OR
$10,0000 give-a-way
Sell chances for $100 each. (For this to work, all families have to sell a certain amount of tickets or buy them.) On a certain night, everyone gathers for dinner and entertainment. Before everything begins, three names are drawn and placed in labeled envelopes-the first drawn name wins $5,000, the second $3,000, and the third $2,000. No one knows who these are until the end of the evening. After the meal and entertainment, a few more names are drawn for door prizes. Then the $2000 winner is announced, the $3000 winner is announced, and the $5000 winner is announced. The person who announces the last winner usually has some fun by having all males who bought a ticket to stand, all males who bought a ticket and have two children remain standing, all males who bought a ticket and have two children who are males remain standing, etc. until only two people are standing. The winner is then annouced. On the tickets that are sold, there is a place for the seller. He/she will get $100 for selling the ticket.
This has been done for many years in a poor rural area for a private school. While I have never been in charge and don't know all of the particulars, I do know that a good bit of money has been raised every year for many years. (Many may consider this gambling, so it may not be appropriate for your situation. Many grandparents who might make contributions anyway have used this method of contributing.