A friend of mine said Best Buy once quoted him $400 to install a flat panel tv wall mount bracket.
I was happy when they delivered my new TV in july, hooked it up, and hauled away the old one for free.
Although $400 isn't cheap, it's not far out of line, IMHO. Did that include the cost of the bracket? They run around $100-150 and up. Installing it correctly and running cables could easily take 2+ hours.