I have always been of the opinion that (assuming you have a cellphone) mifi / personal hotspots / tablets with data is the phones companies way of getting free money from the people that can't configure their cell phone to do it for them. Replace the cell phone with another device that can do the same thing.
Get one service and set it up to share to other devices. Don't fall in the latest ATT rip off and do "mobile sharing plan" which only makes sense if you share with more than one person. The commercial even says the "guy" has a mobile hot spot, tablet and cell phone and can add devices for $10 each! Except if you set up wireless hot spot on the cell phone you could throw the mobile access point out the window and connect the table to the phone and save $20 a month.
Anyway point being, get service on device (the MIFI might be better since it is dedicated to that task) and just bond the tablet to it.