You can get GamePass Ultimate for $1 for 3 Months right now.
That will get you both titles,
I see. I need to look into GamePass if it's really that good of a deal.
But, to clarify, Reach is the first title being released as part of the Master Chief Collection, and is all that's available for now. The other titles will be available as they come out.
edit - I posted based on what I read on the Halo Insider forum, but just checked Steam and realize now the pricing is more inline with what I expected.
Long story short - yes I plan on getting Halo MCC for PC!