Any idea how much about 3 meters would cost?
2x4's are cheap
Really depends on the kind of wood you're getting. The "good looking" wood is not surprisingly going to cost you a lot more (sometimes making your project cost 5 times more). If you're on a budget, as a lot of students are (and it really doesn't have to look beautiful to win), some home improvement or lumber stores sell scrap/damaged wood for less; I think I've seen it at 70% off sometimes. If your device ends up being a bit wobbly, add some metal brackets or add some wood supports to your angles.
"One of the ways that I believe people express their appreciation to the rest of humanity is to make something wonderful and put it out there."