Quote from mgookin:
If this is for trading or trading redundancy, I strongly recommend just paying the monthly fee for an unlimited mobile broadband card. There are some which limit monthly bandwidth for a little cheaper if you're on that tight of a budget, but even the unlimited is cheap for a redundant data connection if you consider the cost of not getting online and taking action in a volatile position. Just look at the cost and annualize it. It's just some overhead.