I had a "wishlist", so I worked my butt off and saved every penny I possibly could. When I'd scratched enough money together, I searched high and low for the best prices I could find on the items I wanted. I ended up buying my 10-22 and 24-105 used through this forum, and obtained these two fine pieces of glass (which looked, felt and functioned as if they were brand new) at a decent discount over retail prices. At the time, I didn't see many 100-400 lenses on the used market, so ended up buying it new (along with a couple other smaller items) from B&H. Conveniently, Canon rebates were in season at the time and that saved me some money too.
I currently shoot with a 7D, but had a 40D before that and an XT before that. I bought the bodies new. When I got the 40D (and 28-135), I sold my XT and 18-55mm lens on this forum to offset the cost. When I bought the 7D (again with the 28-135, as the one that came with my 40D was sold to a friend shortly after I got my 24-105), I sold my gripped 40D and the 28-135 that came with the 7D to a friend. This made the cost to upgrade much more bearable on someone with limited disposable income.
I should note that during the time I was lusting over items not yet in my possession, I was happy with what I had and made it work for me. Although I now have what I'd consider decent gear, I still believe that it's not what you have that makes the shot (or photographer, for that matter) but how you use what you have available to you. I've seen people using the 24-105 on a 5D2 and someone standing next to them with a XS and the kit lens... The person with the XS got the better shot, while the user of the 5D2 was left complaining about how the Auto mode he was using left him with an out-of-focus and overexposed image. He walked away muttering something about a "stupid %$@! expensive piece of *&$@" that was going to be returned because it was "clearly broken".
7D w/ grip, 10-22, 24-105, 100-400, 50/1.8 II, 430EX II -- (40D w/ grip, XT, 18-55, 28-135, 55-200)