If all things in recruiting were equal, equal distance, no favorite school, etc, etc. If a A+ school spent 100k on a recruit how much would a B need to spend to win that battle?

Most of the coaches who have spent a lot of time and effort coming up with what they consider to be a reasonably accurate response to this question aren't going to want to share it with the rest of the world. That said, all else being equal, 200k is probably a good starting estimate.

First off, I assume the OP is asking about D1 (and not D2/D3 as the difference in prestige is way less at the lower levels).

Also, if you are considering fighting for a recruit with an A+ school that is worth that amount of cash (likely a 5 star or good 4 star), then you also need to expect that other A+ schools will also eye both your other recruits and/or even joining that fight if they feel they can win it as well.

So you need to carefully consider are you willing to risk your entire class for this recruit and can you beat any A+ school who might come along (A+ schools could have an even bigger advantage depending on draft picks giving them A+++ level prestige).

Yes it was a division 1 question.

Thanks for the responses.

I am not too worried about other A+ schools. I think the biggest A+ threat is the school currently being considered by that recruit..

It has to be a D1 question (who the heck else is going to have $100K to spend?).

Prestige plays a bigger role at D1 than at D2 and D3, where it is a factor but less intense.

It's also important to note you really can't compare prestige between divisions - even a D- school at D2 is higher prestige than an A+ at D3 (or should be, anyway, and I suspect this to be true).