For 9mm FMJ, anything less than $13 per box (50) is reasonable. Sometimes you can get it as low as $9.50 per box. I tend to buy 500 at a time from ammotogo.com, and the shipping costs are about the same as sales tax, but I don't have to drive 20 miles to get the ammo. But if I am at a gun shop or Cabellas and they have 9mm for less than $13/box, I will always pick up a box or two.
For me, reloading is about performance, not cost. I will reload rifle cartridges to optimize accuracy or other performance aspects. But if I have an extra 2 hours in my busy life, I am far better off to spend it working and making money than I am to spend the time making practice 9mm cartridges.