After buying the 500mm v2 I was too cheap to buy a camo lens coat so bought a sheet of camo neoprene from here http://www.ewetsuits.com/acatalog/camouflage-neoprene-sheets-ukl.html
and made my own. Use their Black Witch neoprene adhesive to bond the seams. The sheet is large enough that I made a coat for my 300mm IS v1 too and still have enough left over to make anther couple of coats. Overall saving was over £100 compared to the price of two "pro" lens coats. Okay, there's the time factor involved too but it was a reasonably straight forward process to make them.
Glad I made them as I was out last weekend when it was a bit cold (some ice on local lake) and the 500mm was fine to hold with my bare hands against the neoprene - I touched the metal body and was amazed at how cold it was! No way could you hold it without some protection....or maybe just a cheap pair of gloves!
One point though - the neoprene is about 3mm thick so neither Canon lens hood now fits and the 500mm won't fit in the flightcase. Ah, well.... Anyway, I use Optech Hood Hats for both as they're cheap and effective.
Also got the Lowepro Lens Trekker AW II - it's okay but I find the velcro collar which holds the lens in place is a bit of a hassle as one part of it seems too deep so that the lens isn't held vertically in the bag, it gets pushed away from vertical - attached pic doesn't show too well but you might get the idea.
Finally, in case you wonder why I got the 500mm rather than the 600mm - it was a mixture of cost, weight and range.
(In the pic below of the two lenses together, the 500mm also has the 1.4x mk3 attached)