On one hand – it's an awful lot of money. That's also what I think when I look at what I have spent on camera equipment (even if my total is still below the price of a 645D body).
But then I remind myself (and my wife) how much some people spend on a motorcycle, a sailing boat or a sports car. In that light, a 645 isn't that much! (If you have the money at all, that is.)
Recently I bought a Wimberley Gimbal II head and a top notch heavy duty carbon fibre tripod (Feisol) to go with it. With this I spent a year's lunch box savings – I spent nearly precise the same sum a friend spent on a new exhaust pipe for his bike :-) If I could afford that bike I'd surely buy myself a 645 instead. And a nice bunch of 645 lenses to go with it. And still have money for an ice cream.