Got a green Flipside 400 for only slightly more than fifty quid a month back from Jessops
Holds a 40D with 400mm attached, room to spare as well also has a waterproof cover and tripod holder
Maybe worth considering?
The Kata 3N1-30 will do that. Excellent for carrying gear with the straps in rucksack config, and of course converts to slingpack when "on site". Very well made too. I got mine from Amazon @ 3 weeks ago for £73 post free.