Jason, my Roadrunner through Time Warner is $50 a month, but that's residential. I'm assuming you are looking for something for the store, and they will probably require a business plan. No clue how much that is.
As far as tethering is concerned, there have been a few things pop up here and there that enabled tethering without JB but they got shut down pretty fast. If you are going to tether without paying for it, avoid ATT as they monitor that shit pretty well. Sprint turns a blind eye and still has unlimited data. Their downside is their 3g speed is shit, 4g isn't so bad if you have it available. And it's way easy to do with an Android device.