Mike,
Hard to say about 5D mk ii prices. I can see them falling in price simply because the bulk of the market wants the newest and latest.
I haven't really been following Nikon D700 prices that much but since the D800 announcement I have seen a number of D700's for sale.
Here is a good site where you can click on various full frame Canon lenses and read the reviews on each. Very handy.
There are also links to Ebay for each of these lenses selling there.
http://www.photozone.de/canon_eos_ff
Greg.