I'm kinda cheap :) And it gives me great satisfaction to make things on my own and save a lot of money!
On the other hand, some of the things have to look nice so you can't always make things yourself. This canopy is going to cost me approximately 30$ US, and thats for the paint. The wood is from a construction site, and from my carpenter roommate.
I'll try to guide you thrugh the process, step by step, and show some pictures too!
I had an old DIY canopy, which I didn't like very much. The fact that I was moving some tanks around the house and setting up a new tank, helped me decide to try and make a new canopy.
I took the old canopy apart, because I was going to use some of the plywood and the light fixture. After taking it apart, I started cutting out an other piece of plywood I got from my roommate.