My only advice is to use thicker glass than 1/4 inch. I'd definitely say use at least 1/2 inch, because that's what mine is (dimensions: 48x24x19). You'll also want to use tempered glass on the bottom at a minimum too, to support the weight of rocks and the water. From what I've been told in the last couple of days, the bottom pane is usually 1/4 inch thicker than the rest, so you should be looking at 3/4 inch tempered glass at the bottom.
I'd probably go w/ buying the tank, then building a nice wood or metal stand and canopy. I'm building my own canopy now. I think that I can do it under $40 with the lighting, which saves me a bundle. I'm on a quest to build one for under $100 total, and since I got the tank/stand for $50, I have only $50 more to spend.
You'd be surprised at the deals out there...really! Like I said, I got my 75G for only 50 bucks w/the stand! Here's the pics of it:
http://www.myfishtank.net/forum/showthread.php?threadid=6876
Look around in the local trading post, newspapers, and online listings. I'm sure you'll find someone who just upgraded, and their wife is demanding that the old one is G O N E !!
If you do decide to build, good luck with it! I'd be interested to see how it's done....be sure to take pics!
Take Care,
Frank