I got a 75 off of craigslist for $150, including the stand. The stand ended up being used for an emergency situation, so I needed another. Truthfully, I planned on making a new one anyway, the other looked, well, old.
I found a thread on reefcentral discussing someone building a stand and he used Google's sketchup to design it. It's a free program, so I gave it a whirl. Took about a week to really get the hang of it.
After figuring the dimensions I wanted, I decided to frame it with 2 x 4s and "skin" it with 3/4" ply. It's probably overkill to some people, but I want to sleep at night. I've added some screen shots from skethup.