Its a frustrating position now...
1) You have waited all this time for an over priced update.
2) You now cant afford the new updated machines, and feel sick at the thought of paying so much money for the base line quad core machine.
3) You try and hunt down a 2008 machine for a realistic price, kicking yourself for not buying one last year, and then kick yourself again for the fact that the 2008 machine is using year old tech... at practically full price.
So the only option I can see is not to buy.. Look into alternatives. I was torn between a top end iMac and a lower end Mac Pro. Neither are now attractive options unfortunately.
Excellent post, I'm in exactly that boat. Alternatives are looking good now, and I bet you can guess which alternative I have in mind.