I use Verizon pre-paid, and tethering is included free. You can add-on data-packs that roll-over for up to three months as needed, and I use a LittleSnitch pro

I use Verizon pre-paid, and tethering is included free. You can add-on data-packs that roll-over for up to three months as needed, and I use a LittleSnitch profile to curtail things like backup services and other heavy-data use services when I'm tethered.