How to organize the acceptance of payments for a one-time event without the hassle?

Question

Payment systems

I am developing a one-time event - something like Secret Santa. We need a payment system so that users pay for gifts that will later be distributed between them. As you can see, the project is not aimed at making money at all, it is relevant for a week of the year, and it’s natural that you don’t want to draw up a bunch of paperwork / start a long relationship with online cash desks, that’s right at all.
Tell me, please, how can you accept amounts generated on the fly without much hassle, long-term prospects, obligations and paperwork?

PS The question was re-uploaded after deletion because of the extra "programming" tag.