A lot of these guys are shooting full frame.. you can get similar results on APS-C for a lot less (I note you are using a 30D)
Check out the 200mm f2.8 L II (behaves like a 320mm f2. and is an excellent sharp lens on APS-C.
Also check out the 100mm f2.0 USM (behaves like 160 f2.0) and is also an excellent sharp lens on APS-C.
At vastly cheaper prices than the big boys. Don't get me wrong the big boys are brilliant and better... but you don't have to remortgage the house to get some very very nice canon glass, especially if you are shooting on APS-C!
Thanks for the advice, Paul. I'm an amateur photographer, and a camera and lens repair hobbyist. What is normally a fairly expensive hobby (photography), I have managed to get into pretty cheap by buying really good deals, and repairing broken equipment. I'm not looking to get any L lenses right now, but I definitely appreciate the beautiful images they can create. That's why I'm so excited about my 85mm f/1.8 that's on it's way now, it's an inexpensive and fast lens that has nearly-L image quality.