For Coach payroll I usually go with 14 million. I prefer to have top coaches at all levels for development and sacrifice in other areas to do this. As for prospect payroll, I try to max it out at 20 million. Dedicate 7-8 million for signing draft players, and the rest for international free agents. Sometimes player payroll doesn't allow for high prospect payroll.....year by year case.
With 12-13 million for internation free agents, sometimes you can pick up a fairly quailty Major leaguer if you don't get into a bidding war where the signing bonus goes through the roof.