Well it depends on the recruit, how your running your team, what kind of budget you have to start with, and how many schollies you have to fill.
I don't think there is a set amount to spend, depends on the coach and his style.
My spending on average in DIII is around 2k - $2,500, and I would say in DII would be around $3,500 - $4,500 on average. Although I have signed guys for less, and more just depends on the recruit, and if your battling anyone.
Hope this helps and I am sure the other great coaches out there will chime in.