Hi swerner
I assembled a 400 gal tank from glass panels. Like several members told you glass bought locally will cost you more then the finished tank. Here in Edmonton one fish store has a connection to a glass factory in China, because of this all my glass and shipping by boat was only 380 dollars. They regularly take orders for glass kits and it takes 1 month to receive. Some of the tanks are up to 650 gallons. My glass is 5/8 thick and the dimensions are 96"x32"x32" roughly 425 gals.The actual job of putting the tank together is really straight forward, I used toothpicks to space the glass then forced GE1 silicone into the space. The whole job took 2 weeks , I gave each joint 24 hours to cure before going to the next one. Filling the tank for the first time was nerve racking knowing that there is 4000 lbs of water and only 5/8 inch of silicone stopping the front panel from bashing my head in. Everything did hold and all is good. If you can find cheap glass this is for sure the way to go. If you need any further help please ask
Mark
PS Here are some pics