<".. investing almost $100 million to get a 35% interest at this early stage.">
The farminees have the opportunity to back out after the first 5 wells, estimated to cost around A$64 million, so that 32 mil net to Sasol. Add in $10 mil for the up front payment, and your talking about apprx. a $42 milllion committment at this point, not $100 million. (and perhaps a bit less, given currency conversions).
Plus, just to put it in perpective, Sasol is a $37 billion company, so this represents a rather modest financial outlay for them at this point.
(Note, I'm personally optimistic about the Beetaloo play, and believe it could eventially become a world class basin, however, it's going to take a VERY long time.)
jmo