Unfortunately it isn’t that simple. A lot of these lenses are expensive not just due to rarity but from the shear complexity and difficulty in producing them. Some can take literally months of production time. They frequently contain dozens of pieces of specialised glass which are ground to tolerances measured in nanometers. The way the light interacts with these lenses is simply not something that you can simulate. At least not on anything less than a decent sized supercomputer.

And the reason you want one of these expensive lenses, is that they can do things that other lenses physically cannot and can never be persuaded to do.

The famous Carl Zeiss Planar 50 mm f0. 7 lens used in Barry Lyndon is special because it can physically let more light into your camera than any other lens. That’s why nasa commissioned a set of them from Zeiss to use in filming the moon landing.