Even I use T-Mobile.

But recently Virgin (I believe) bought out a Mifi device with unlimited 3G data (true unlimited - no 5GB limited crap like Verizon) a month for $40 flat. And it runs on top of the Sprint network - so OK coverage at that. Sprint it seems is pushing their 4G and hence is willing to see their 3G to Virgin.

So if someone is alone you could possible use this as a home and on the move intenet plan (albeit not as fast as wifi) and then use this to tether as many devices (or maybe a limit to 5 devices at a time) over wifi.

I like this solution - and hence my wish for a Wifi only Tablet - which I could tether to my existing N900 or a Mifi device maybe in the future.

Edit : Forgot to add the big point - Virgin Mifi plan is a no-contract plan - so you could use as needed and cancel and get back on again on a month-to month type of plan.