Paying for grades and pictures

Years ago, when my children were just starting into junior high and high school, I decided to motivate them to get good grades.
Foolishly I offered $5 per A on their report cards — not realizing how many As came on each card and how often report cards came out.
Multiply that by six pretty good students and I was facing a national debt-type crisis in my pocketbook.
I couldn't keep up.
I felt bad later when I had to pull back and just offer a hearty "Good job!" instead of cash.
(A similar thing had happened with my oldest son who liked video games. I had told him he could get a new game for each good report and very quickly got into trouble there. He made out like a bandit for a while.)
Even today when my kids have their own kids, they tease me about it but none of them have made the same financial mistake.
It seems I always underestimate what people will do for monetary compensation and the hit on my budget.
(I'm not alone in my faulty promise-making. One year, Ski Utah offered free ski passes to high school kids with 3.5 GPAs and my middle son who never cared about his grades before suddenly hit the books and passed all the tests and earned a ski pass! So did a whole lot of other kids in the state so Ski Utah had to pull back on its offer.)
(I also think the airlines and credit card companies start out with good intentions with their reward programs but quickly pull back when they have to pay up.)
Now, I've started a reward system with my husband that bears the same kind of potential for trouble.
I told Marc he ought to feel like he could buy a new Kindle book each time he took photos for me when I went on stories. He does a good job and takes time out of his busy days to help me, after all.
But that's getting out of hand even though I added, "for published pictures" to the criteria.
I owe him for about five pictures now and I'm getting grumpy when he reminds me about it. It sort of defeats the purpose of having a freebie photographer.
Maybe it needs to be "for really good published pictures that I feel like acknowledging when there's plenty of money in the budget?"