^ A few points:
1. I'd argue that the majority of the people who would buy the r-pi (not including the ones donated to charity or sent to schools) would not be in need of a keyboard or mouse, and probably would not need any additional internet equipment (though that's no reason not to offer them)
2. Most of the prices you listed above are for retail components. A quick look on eBay will show you plenty of keyboards and mice for $2 or so each, not including shipping. These would also be much cheaper if bought in bulk. Agreed, they might not be of the highest quality, but that can be worked around.
3. Likewise, 7" LCD monitors can be found for ~$100. Yes, these are no-brand ones with probably average quality, but we're talking about assembling a complete package as cheaply as possible. I didn't look extensively to find these, and they are e-tail prices, so naturally cheaper options would be available if, like you say, the Foundation 'needs' to offer these.
My point is simply that your prices may not be accurate for what a user would necessarily have to pay, especially if they were unafraid of buying on eBay or elsewhere online.
In spite of what might seem as a negative view towards your post, I heartily agree that for many people the major cost will be related to the accessories that they are able to buy, and as such I think it would be a good step to offer such a 'package', though I do not know how practical that would be from the point of view of the Foundation (I have read somewhere that thet are thinking of sourcing some peripherals, but I do not want to make any assumptions/statements that could be misconstrued as being 'official' - I'll link to the info if I find it).
EDIT: Also, see this thread: