"Paying a college student $9/hr is a win-win in my opinion."

If you find college students who actually know shit about computers might they not have some other means for making better than $9/hr?

I have no idea what the market is like for these things, but I'm wondering if you'd be better off somewhat overpaying and making sure you had people you could trust to sort out problems when some repair routine doesn't quite work.

They might, but will they? My experience is that most people really don't want to run businesses. They want to come to work, do the job, get paid and go home. Most also go for a comfortable lifestyle rather than absolutely maximizing their income (too much work!). In that case, the college student who likes computers will probably choose to work in that field for $9/hour rather than for $10/hour at WalMart.