Think I'd call your dealer and have him deal with it. I know my other M9 (I have 2) is a cab model and there is a lot of stuff (electrical) up there.
1400 is pretty steep for a blow moulded plastic top but after I just paid 175 bucks x 2 for new tie rod ends I can understand the price. Do I accept it as a good value, certainly not but it is what it is.
I am curious as to how it came off. Mine is held on with a number of screws through the roll cage. If I remember correctly, there are 8 machine screws that secure it.
Puts me in mind of the time I was stupid and left the drivers side door open and hooked it on a fence post. The glass exploded and I was left with a handle 2 hinges and a rubber gasket and a pile of glass. That stupid moment cost me $997 and change. My deductible on my farm policy is a grand so I ate the glass. Needless to say I make sure the door is closed now.