As others have indicated boat based internet is expensive.
Here's how we do it.
We have a Cradlepoint MBR1200B router on the boat (
www.cradlepoint.com)
What this device does is choose between AT&T and the KVH Vsat system.
When within range we use AT&T. We have a 60GB shared data plan that we use for all our devices and currently pay $3.50 per GB. Data rates are coming down, and we expect that rate will decrease over time.
When out of range of AT&T, which is often in the summer we use the KVH MiniVsat service. The cheapest rate we have been able to get from them is $0.49 per MB, and that requires a 2GB monthly commitment. At a thousand dollars a month or more for that service the only way we can justify it is to run our business. We consider it a cost of doing business. It allows us to conduct business while at sea, keeping us from having to staff the office.
I am going to guesstimate that 90% plus of boaters here on TF will be within cellular range 90% of the time. That makes cell based internet a viable option.