Weight varies greatly with glass tanks from different companies. My tank from Glasscages.com Is over 500 lbs and it only measures 72x30x25 (inches)... takes no less than 5 people to move it, but 7 is optimal... WATCH YOUR FINGERS putting into the stand..According to this online aquarium glass thickness calculator, 10mm glass should work for a tank that's 10'x4'x2'.
http://www.theaquatools.com/building-your-aquarium
A glass tank that size is going to weigh over 500lbs.
I would try to find a local glass shop/aquarium builder to get an estimate.
Around here a brand new glass or acrylic tank that size will break your budget several times over.