A separate lunar lander is needed because the Orion capsule that would sit on an SLS (Space Launch System) rocket cannot land on the moon. Lockheed wants tens of billions to possibly get the SLS and Orion flying and then tens of billions for $150 billion for the lunar gateway in orbit around the moon and then more billions for lunar lander.
The lander would accommodate a crew of four and 2,000 lbs. of cargo payload on the surface for up to two weeks before returning to the Gateway without refueling on the surface.
It would have dry weight of about 24 tons and a fueled weight of 60+ tons.
The manned Orion capsule is currently tracking to about $20 billion in cost. This Lockheed proposed lunar lander is much bigger than Orion and has new liquid oxygen and liquid hydrogen propulsion. It looks to me like it would easily rack up $40 billion in cost based on the Lockheed cost track record.