Set fair spending limits for a secret santa group.
The whole point of secret santa is that each person buys one gift rather than one for everybody, and this quantifies that. Your cost is the spending limit plus wrapping plus an even share of any party expense. The saving line shows the alternative: in a group of twelve, buying for everyone means eleven gifts, so the arrangement saves each person roughly ten times the gift limit. That is also the argument for setting the limit generously — one good gift beats eleven token ones at the same total spend.
Your cost
Your cost = spending limit + wrapping + shared party cost / participants
The saving
Buying for everyone would cost (limit + wrapping) x (participants - 1) plus your party share
High enough to buy one decent thing — in most workplaces that means the limit people actually respect rather than the lowest that seems polite. A limit so low that gifts become joke items defeats the purpose.
Yes, and it is worth saying so up front. Wrapping paper, name draws and any venue booking are group costs, which is why the party expense here is divided evenly rather than absorbed by one person.