Depends on the distance and when it is. My impression (can't really back this up, but I think it's true) is their magic number drops slowly during recruiting. So a guy who would've taken 15 might take 10 a couple days into recruiting.
But I would say anything less than about 8-10 SVs and you're probably wasting your time..however much it costs you to do that. If he's close by, that might be less than 2000, but that escalates in a hurry if he's not close.
I'm amazed at some of these 30+, 40+ responses. I've never done more than about 20 myself..and that was only when someone else was definitely trying to pull him down at the same time. I guess I could see it getting out of hand if neither coach backed down.