Newbie question

What is the ‘tub’? - and why does it cost so much ?? I thought it was a piece of bodywork, butclearly not so sure now.
Any easy way of telling whether it is cracked ?

The ‘tub’ is the aluminium chassis that is the core structure of the car. If its cracked it will most likely be visable. Does the car you are reffering to have accident damage? If so why don’t you post up some detail pics and we can advise if the tub is damaged.

Just a query, but thanks all the same for the reply mate!