I don't recall the details. It's not just shipping -- unlike Amazon, Google actually charges sales tax (not a criticism of Google btw -- I think Amazon's sales tax advantage is horribly unfair to other retailers). For the model I eventually did buy (16GB, which was at that time the top-of-the-line) I paid about $25 in shipping and tax.
What I can verify is that I paid $275.44 for a "$249" 16GB Nexus 7 whereas a Kindle Fire HD would actually be $199.
Like other businesses, Amazon collects sales tax in states where it has a physical presence (which is a probably a different list of states than for Google). For example, New York State residents pay sales tax on Amazon.
It's amazing that a complete computer with screen and a multitouch interface sells for $275 or $199. $200 is how much a couple people can easily spend in one day at Disneyworld, or the price of a night at a decent hotel and a couple restaurant meals.
What I can verify is that I paid $275.44 for a "$249" 16GB Nexus 7 whereas a Kindle Fire HD would actually be $199.