Yeah, that is big. Probably the reason it is custom built, is if I were paying for that size, it would be the new front projection T.V. instead. Much cheaper and bigger. The home theater ones.
http://www.crutchfieldadvisor.com/ISEO-rgbtcspd/learningcenter/home/front_projection_TVs.html
For $70,000 I could do it up right, sound system and all for under $20k.