It's not a problem that they are charging $0.99 and $1.99 for certain 300 or so blogs. That is fine as long as that is what the blog publisher wants.
But for all the millions of other blogs, Amazon will never be able to get deals with every blog publisher, that's why they should provide an open blog RSS aggregator where they may charge the transfers per-GB for example. Even something like $5 per GB would be reasonable. This way Amazon has got the wireless data transfer costs covered.
To cover costs, Amazon should also offer ebook optimized advertising, so blog publishers can also sign up for that if they want instead of forcing the readership to pay the 1-2 dollar subscription.