I have quite some experiance buying second hand camera gear, and one thing i noticed might bemefit your goal. Some people buy into the hobby and then suddenly want out, selling all their gear at once. So if you can afford investing, buy somebodys kit (i'd say containing the 7d and 70-200 II) and sell all the lenses seperately. You will have the gear you need for your trip, and make a profit in the process.
Thanks but there are no 7D+70-200 kits. I got a good deal with a new 70-200 IS II, I´ll get the 7D second hand later on. The camera I will certianly sell.