How much for new purlin or other fix?

We are in the process of buying a house that has an issue with the purlin. Below is what the structural surveyor said about it:

1. The purlin is a definite issue. The original purlin has split and deflected, and the splice strengthening is inadequate. It needs a new full length purlin installing + some cross collars and/or props.

Does anyone have an idea of how much this would likely cost? It is a mid terrace and so the new purlin would have to be in two parts rather than a full replacement in one go.

Pic: https://ibb.co/s6tfQ9W

 

That may also be a problem as the wall that runs underneath it is also mentioned in the survey as possibly being an issue. He said

1. There is deflection to the rear of the landing. The rear bedroom and bathroom door frames are out of square and I cannot see how the solid masonry wall between the bathroom and rear bedroom is supported. Perhaps there is a beam in the floor depth, but we don’t know that.