As tech advances so does the price tag right along with it. All the different socket changes along with all the other new parts required for the new tech/build is getting just a little on the expensive side don't you think.
Not any more than it always has been... prices go down, but "they" find new things to sell us so we end up paying roughly the same. Had I upgraded anything on my P4 Northwood it would of been just as bad... socket 478 to LGA 775, DDR to DDR2, AGP to PCIe....
I skipped all of those by keeping my Pentium 4 2.8GHz Northwood Abit IS7 mainboard for a bit over three years, then I built a new rig with an E6300+965P-DS3. Then I got bitten rather hard by the tech bug, couldn't say no to a Q6600... was so impressed with the overclocking on the 3-vReg/3phase DS3 that I sprung for a P35-DQ6 to pair with it.
Upgrading once a year is expensive, most definitely. If Nehalem lives up to the huge potential, I am going to try and buy a high-end board+CPU+GPU just once, and simply keep it for another 2-3 years like I did with my first system. X6800 Conroe came out 1.5 years ago, and it's still a good chip that can do 4GHz... makes all the hype on Penryn just seem a little overblown.
I don't see any reason to be interested in 32nm Westmere (Shrunken Nehalem), so buying a high-end Nehalem when they first come out and keeping it until 32nm "Sandy Bridge", another completely new architecture arrives seems like the best way to go. Which will definitely be 2 years post Nehalem's debut, longer if Intel has another repeat of their current severe shortage of Yorkfields...