You are saying $2b to electrify, add rolling stock (how much?), and add four new stations (including physical integration at Leslie/Oriole, adding one at Eglinton, and maybe doing something at Finch)?
You got to rebuild the line for 2/3 tracks just for GO to get higher speed.
You got to do the rail grade separation at Snider.
Got to do road grade separations along the line.
CN Runs trains on the sub in the Valley and therefore you need a track just for it as well the Northlander.
Adding tracks in the Don Valley will not be cheap. This includes more bridges also.
John, Eglinton, Lawrence, Queen/King/West Don Land, Don Mills are new station with relocation of a few others to better connected to transit.
If you are running 5 car EMU's, that just over $20m a set and you are going to need how many if you are running 5-10 minute headway all day??
How many spares are you going to have?
If the line is a 7/24, how many sets do you need to keep the line operating 100%??
I going on the high side for cost. If you want to go cheap, Just over a Billion, but far less than the $4B for the Yonge extension that includes the cost of the yard that is missing at this time.
The RH line is up and running by 2012-13 where the subway is still 5 years away at best at that time. The EA for this will have to be a Fed one, not Provincial one that has a longer lead time.