Sorry but a lot of this stuff is misleading.
First, without actual figures on what % of the market is > $1000 versus the rest of the market, or figures on what % of retail market is of the entire computer-buying market, we have no actual figures of how much growth there is.
For example, HP Dell Lenovo etc. make the majority of their money off enterprise sales. Considering that Apple barely makes a dent in the business sector of PC hardware and software, and that almost the entire world's business is run off that stuff, I'd say its a pretty sizable market that is ignored. As someone stated earlier in this thread, with business contracts, a $2000 notebook might be < $1000 since they're being bought in volume.
Yes profit margins might be lower at < $1000, but you're kidding yourself if you don't believe companies can't be profitable with volume sales. For instance, whenever Intel rolls out a new chip, that first wafer may cost millions to make, but each chip afterwards will cost only hundreds of dollars. Its also why the Intel Extreme processors cost $1000+ while the regular Core 2 Quad processors cost hundreds, but I don't see Intel losing profits off that.
Also, one big factor to count into all this data is the fact that hardware prices have dropped while Macs have not, despite using similar hardware. You're kidding yourself if you think that Apple is getting hardware that is that much better - they're all manufactured by the same companies in factories in China. Quality might differ a bit, but if you look into PC hardware, getting a high quality reliable motherboard vs. a budget one of the same chipset rarely varies by more than $100. And that's retail pricing.
Also, hardware prices have dropped big if you think about it. Back 3 years ago, getting a premium notebook could cost you $2000+. Now? You'll get a great performing one (non-gaming etc.) for < $1000 easily. Heck, $400-600 notebooks can be found regularly now.
Also, look at PC's - you can get a Q6600 quad cored PC from Dell etc. for $600 now. If you build your own, you can build a mean rig for $600. For that same performance even a year ago (and trust me, I know cause I built one then), it would've cost you $1300+. Look at DDR2 RAM prices to just know how much they dropped as well (from $150 for 2GB 1 year ago this time to practically free). Think about a Q6600 1 year ago this date - it was $530. Today? $200.
Finally, look at market trends. First, PC gaming has been agonizing because PC game developers are moving to consoles. Part of this is because consoles have become more powerful, and the other part is because most people are tech illiterate. Thus those who are likely to buy a premium PC for home use (usually gaming) is decreasing. Workstations are another story.
Next, those who do game these days tend to build their own PC's, because for $800 you can get a better PC than a pre-built one for $1200 easily. This isn't about manufacturers captivating users or not - people who aren't sure about building their own computer will still go to manufacturers. If you look at big parts sellers like Newegg, revenue has been huge from the large # of people learning to build PC's. Really, build one once and you won't forget how to do it.
And with market trends, if the majority of the market buys computers for casual home use, then the fact that you can build a budget PC for $400 these days (even thats too much, I just built one for $300 and its dual core and all that jazz) will not help the cause for > $1000 computers.
Thus, without any reliable information on what percentage of each market belongs to the rest of the market, all this stuff doesn't prove anything in terms of how much stuff is actually being sold and how many people are using it.