A new 5D Mk-II body from D-D-P is $2,845 Mike - bare. That's one of the lowest prices here in Oz, but some others might have it a little cheaper on the day. Selling both 40D's would possibly get you just over half way there. I sold my 40D a little while ago and only managed $700 with lens and other accessories. Maybe one of yours is worth more to a buyer modded.
My main lens is a 24-105mm EF F4.0 IS USM and it's fantastic on the 5DII. My shot of the girl in the rock was taken with it as was the fisherman shot in this month's comp.
Not sure about your Sigma - I know nothing about them.