What hole did you pull these values out of? I'd say cut each of your numbers by half, and you'll be a little closer to accurate.
Anyhow, to answer the question of value, technology is priced comparable to market, not based on cost. If that were the case, batteries would all cost $0.10 for a 8 pack of AAs, and HDMI cables at Best Buy would all be $2...
Price is set by demand and market allowance\competition. Apple's competitors based on size\features are priced about where the MB Air is, which is how Apple sets their price.
Well of course they don't sell their products at the same cost it costs them to produce it! I'm talking about its market value. Are you that blind? Do you really not understand the concept of market value? Or are you trying to teach it to me? Because I just demonstrated what market value means. The screen is worth about $100 at market value. Why? Because it's high quality. Don't go lecturing me about how it costs them less to produce: Every product sold on the market costs less to produce than its sold for (with the few exceptions). That's a given. But I'm arguing the point that the Macbook Air is not overpriced, and actually isn't priced at a premium for its looks... that every part in it at its respective market value adds up to the correct amount. When you add the price of every part thrown into the Macbook Air, there's no extra $500 price tagged on just for it being an Air. Of course you end up paying some premiums for certain upgrades.
The OS is worth $50, plain and simple. They're selling it for $30, but that requires that you already have Snow Leopard before-hand. So I'd say $50 is a conservative value.
The screen is obviously worth $100. Look at the quality of it. You'd be a fool to say it's worth less. Yes, of course it costs Apple less to produce: It's called retail. They don't run a charity. You can't get a basic laser mouse for the $1 it costs companies to make them, or a fancy mouse for the $5 that it costs them.
The casing again, is worth about $100. This is the one where you might go a bit lower on the estimates. But look at the cost of a nice iPad case (when I say case here I'm talking about the leather cases or otherwise that you put over them), or a nice Macbook case, or anything else... you're looking at around $50. And those cases aren't made of trade-secret assembled aluminum (or aluminium or whatever it is).
Keyboard & Touchpad: Again, together these are about worth $100. Again, you could argue that it's just slightly less. But the touchpad is extremely large and extremely nice. To buy such a thing (for USB), you're looking at $60-$70. The keyboard is also very nice quality. One could argue together they're only worth $80-ish, but still... rough estimate. I value them together at about $100 if I were able to assemble every part of my laptop in a custom manner.
Processor: I based this on the low-mid end mobile processors by Intel. Maybe you're just misinformed, but why don't you look at their price-points? The suggested retail value of their chips are between $180 and $300. I'm talking about the 17W chips and 25W chips.
Motherboard & Misc Internals: Why don't you look at the price of decent motherboards and get back to me. I assemble and repair computers for friends & family regularly (between 5 and 10 in a year usually). Usually these are basic desktops, or gaming rigs. The cost of even a basic motherboard is going to be about $60 for anything functional and old. An up-to-date motherboard with recent technologies built in is going to cost more (a basic Sandy Bridge motherboard for a desktop starts at just above $100, and something of decent quality in a desktop can't be bought for less than $130... on initial release, you were looking at $140-$150 minimum). My estimate of $150 is quite reasonable. That's including the cost of the bluetooth, the motherboard, assuming thunderbolt is in there as well, the built-in wireless, etc, etc.
RAM: I gave a very conservative price on this. Again, I'm assuming 4GB of RAM will be baseline. I said it's worth $50. Based on a bit of an assumption here.
SSD: Why don't you look at the price of a quality SSD and get back to me. Don't reference a cheap OCZ SSD or a Corsair or anything of the like. Apple purchases products based on A-grade quality (for the most part). If they bought OCZ SSD's, Macbook Airs would be failing left right and center. $150 is a very good estimate.
Facetime Camera: I think $30 is a great estimate. In fact, if they up the quality of the facetime camera, I think its value is a little higher. I just picked $30 to round off my total to $950 in the end.
So there's where I got my numbers from. All these numbers are informed. And I did disclaim in my post that they are rough numbers just for a general idea. Now don't you feel foolish?