It's isn't the speed, (which might be enough depending on how they use it), I'm finding the 30 GB laughable! 

I pay $65 a month plus taxes, I bought my own modem and an AirPort Extreme Router. 

As I mentioned I have "loosely" capped 300 GB at 25 mbps.   The next tier up only adds 100 GB a month, and we're just close to 300 without thinking about it, so no worries.

If OP uses Netflix or any internet gaming, that 30 GBs is toast in a few days.