First bill is always an eye popper. Mine certainly was, but then I knew it was coming long before the flatbed pulled in front of the house and the guy with the forklift dropped it on my doorstep. That's just the nature of the process. After that first experience, your bill should level off to a steady predictable amount that's pretty much what you expected from the start.
A word on taxes. I'm from Oklahoma. Oklahoma hasn't taxed the Internet just yet, but I'm sure they'll start getting ideas before too much longer. There's also taxes on the modem lease, taxes on the pole, taxes on everything except the service. Sometimes the tax is actually calculated on an area different from where you live such as the installer's home office in another town since that's how the installer has to report and pay sales tax. If it gets too much out of line, my own experience is that customer service is always happy to look into the taxes and make any adjustments necessary to correct the issue. That's what they did for me two years ago when I first came on board without me even asking. They're pretty decent folks.
Now on T-1 service; enjoyed my time at WildBlue and still a HughesNet defectee.