Just estimates, buddy. I'm sure the accounting types will be able to account for all the sales tax, labor, fuel, etc, etc... I think the MM estimate of $150/ft factored all that in, but who knows.
I'm more of the manager type anyway, not the geek type ;)
Thanks, amigo. Sorry for the harsh tone, but I have a feeling that there are ways to do it for much less, especially if private citizens do it. If the government does it, you're probably right on the money.