Clive there is a thread where this and related topics were discussed ad nauseum, but I'd rather not rekindle that thread because it contained some unpleasant back-and-forth before it was resolved. The end result was an agreement by some of our nicest and most reasonable members to help put it all together.
The main point is there is a very good initiative in progress, which is just waiting for Sean's input. There is very little to say about cost and numbers etc. at this stage.... it is more an issue of setting up the review structure etc. I think all we can say now is that there will be a very nice book and it will be affordable. And it will have broad participation.
P.S. Sean = our benevolent site owner who is very busy