From the announcement:
Pre tax NPV at 10% discount rate of between $180mill-$500mill.
Let's assume it's worth the mid-point, around $350 mill.
Add the cash in the bank (@ $100 mill) and we can justify a NPV of $450 mill.
Bring on a good deal at Bungaroo and I see a justifiable case for NPV around $1 billion.
Just my 2c worth.