fair valuation

Has anybody got an understanding on how they reached fair valuation?
From what I see the figures of
10.5 c/ps = low
15.0 c/ps = prefferred
23.5 c/ps = High
all they refer to is what the market is prepared to pay...at the high end there was lots of speculation and I dont think anyone was expecting pp to take such a large chunk(NB my high limit was 69%...see past posts)
Since then the market has acted accordingly seeing us at approx 11.0 c/ps
But is this fair valuation?
Then in the report they value the Balmoral Rights at
$170 000 000 = low
$273 000 000 = preffered
$594 000 000 = high
where do they get these figures and with a range as big as that (over a 300% differrence) what number do you go with??