Cost plus is only defensible if the goal is short-term and all-important. If an asteroid were barreling towards Earth, yeah, sure, throw a trillion dollars at it.
An open-ended goal of expanding the scope of human endeavor in space (and this landing is just a manifestation of the bigger goal) requires building an efficient industry around the goal. To that end cost-plus must go.
I recently moved to a Pioneer Altitude Billfold. Great if you are looking for something that handles cash well and is still compact. Nylon, not leather, but still very stiff and luxurious feeling.