My New Year's resolution last year was "I will not spend more than $2000 on a small format camera body ever again." When I shot film I used gear that was decades old because it worked great, but cost significantly less (except the collectible stuff like Leica). Digital image quality is good enough now that I am very content with supposedly obsolete gear. I think the EOS 5D mk I is a lot better deal at $1500 than the mk II is at $2500. I probably won't ever buy a Nikon D3x, but when the D700x that they will introduce soon drops below $2K I'm there!
A guy I do contract photo work for recently let my use his Mark II with a 70-200 f2.8L USM. The camera is awesome! You can get a used one on eBay for about $2500 or so. It's not too much! The lens is just too expensive though. I just got the 7D myself, which is pretty wicked. Only thing it doesnt have that I loved about the Mark II was the fact you can put both a CF and SD card in at the same time and pick which to shoot too. Other than that, I love my camera as well. Well, that's cuz I was shooting with a 20D for about 5 years. =D
I love my Canon 5D to bits but use it at the very edge of its capabilities in low light photography - the 5D II beckons if it really is able to do that little bit more it says on the can.......but I'm waiting for the price drop........