Just wanted to ask what country you're from? The reason is, in the UK BT offers BTFON/BT Openzone as part of a free service when you take out one of their broadband packages.
My uncle uses BT and I live about 100 miles away from him. He has log in details for BTFON hotspots which are scattered all over the country. I use Internet from next-door who are BT customers and it is totally above board. Sounds like it may be cheaper than MiFi and I can use it wherever I go (in the uk). If you live here you're all set, if you live elsewhere have you checked out to see if a provider is offering this service?
Just thought I would put my 2 pence in lol. :-D