That's presuming they don't already have a cell phone and intend to use mobile data. If they already have a phone (extremely likely), their cost would be more realistically $75 (mid-range Android phone) + 15-30$ a month depending on data plan. And if they have wired Internet and don't want to change up phones, they can simply use an iPod touch ($230 once) and use their existing connection (already paid for).
I don't know who you mean by small business owner. I am sure high end small business owners(coffee shops, bars, night clubs) will eat it up and agree with it. I am talking about taco truck, etc.
If there are many transactions/customers, which would be cost effective for the SBO, the data usage might go over the limit, and I am sure ATT/Verizon will have something up their sleeve to over charge(apart from the $30/month) which would make this less appealing, apart from the already high transaction cost.
This objection is idiotic. The number of transactions required to go over a 2GB limit would be in the millions. A 200mb limit would still be in the thousands if not tens of thousands.
On the off-chance you're not trolling, Square wouldn't be processing all the transactions with a single android phone. The other poster's idea was that individual small-business owner would each have a device.