You can check his open scholarships to get a base line (the amounts per scholarship in each division are laid out in the FAQ and player guide). If you wanted to go further you could check how many games his conference members played in the post season tournament and the reward for those games (again in the FAQ and player guide) and divide that by the number of conference members (at least I'm pretty sure that's how that part works).
The part you'll never be able to know is how much he potentially rolled over from the season before (unless it's that coaches first season at that school in which case he would have none). As well as how much or whether at all he spent on future stars.
I find open scholarships to be the most helpful, if a team has a lot of open scholarships for that season I assume the coach has a more spread out approach and may be willing to let a recruit go without much of a fight because he will have other options. Coaches going for less players in a cycle may be more zeroed in and committed to getting that one recruit and spending whatever they can to get him. At least that's how I feel but there isn't an exact science to how other coaches are going to recruit.
Hope this helped a little at least.