If your tag line is "The World's first $9 computer" I don't think it's totally unreasonable for people to point out that you have to pay more than $9 to get the thing.
I do, but I expect the shipping and tax to be displayed upfront, before I enter any personal information (aside from address) or sign in/sign up for an account.
Many times the website needs your address to know the shipping, it's quite different sending the thing to an island in the middle of the pacific ocean or to a major US city.
They must be Amazon Prime members.