My dd's Catholic elementary school also has a scrip program. Each family must purchase $3500 in scrip per year. We do not get any rebate from it, all profits from that go directly to the school. If you buy more than $3500 I think the profit from the surplus amount goes toward next year's tuition.
We have a school of between 500 and 600 families. A large amount of scrip is kept "in stock" meaning they have it right there and you can go and buy it. Everything from five different grocery stores, gas stations, dunkin donuts, Macys, TGIF, Applebees, Sears, Lowes, Home Depot, local pizza restarants, etc. is all in stock. (well, technically...sometimes they run out.) There are also other places you can order by Tuesday and it is delivered I think a week later.
The in stock scrip can be purchased Monday to Friday, from 9-4 at the parish rectory, and then from 4-8 pm at the school auditorium/gym where activities are going on every weeknight (sports practices, meetings, etc.) I think they realized that if they expect everyone to buy $3500 worth they have to make it relatively convenient to purchase.
Example, our washing machine broke over the weekend, I bought $500 in scrip on Monday and bought a replacement at Lowes.
Our school doesn't accept credit cards for scrip and I know some people have requested that. I think they are working on it.
It has worked out well for the school. There was resistance at first like there is with anything new, but once you get used to the idea of it it's not bad at all. You are not spending anything extra, yet the school is making money.
Edited to add, they also allow other people to purchase scrip and have the amount credited to you. So if my parents, sister or neighbor bought scrip, they could indicate my dd's name on the order form and the amount of their purchase would be credited to my account.