Oh you're right, photography is a pretty expensive hobby.
Talking about tripods, I own a pretty basic Vivitar tripod, which cost about $35, obviously not the best quality, and I've really begun to notice that I should invest in a better tripod. I've broken mine twice already and I've had to glue it back in place. Also, with my SX20, the camera balanced pretty well, it was good enough. But now with my T3i, it feels unbalanced and pretty wobbly, and that's using the kit lens, I can't imagine it with a telephoto lens.
But honestly, I don't believe what your instructor said about the tripod being lighter than the camera. I once borrowed a carbon-fiber tripod, it was surprisingly light, but also very sturdy.
I think what you should look for in a tripod are 3 things: weight, sturdiness and durability. Oh, and also you need to buy tripod heads for the more expensive ones.
Why is it all so complicated?