When I graduated (many moons ago! Lol!), I received money in various amounts from people. I grew up in a lower-middle class family, and so I didn't receive piles of cash or anything.
But what I remember being most tickled about getting were the huge bouquets of flowers I got from my Mom and a close family friend! They were personalized with ribbons they had put on themselves, and nice cards.
To this day I don't remember how much money I got, but I do remember those flowers.
I think that flowers have a way of making most girls see past getting a lesser money amount.
So maybe some flowers with $20 for the neighbor, and $20-40 per kid for the others?