Cheapest way to add material tint variation?

[LeonFrei96]

This image is pretty much exactly what I want to do; Modular meshes with a tilable brick texture with lighter and darker splotches across it.
Without changing anything but the base color, what is the cheapest way to add tint variations across modular meshes?
Should I just subdivide the walls, create a master material with different brick tints and paint across it?
The level is about 200m by 200m and uses 1k textures, if that matters at all.

[PedroPalmer]

You should multiply the base color, and lerp it with the original one, using the vertex color as the alpha. Then you paint the vertex on the mesh.

[ClockworkOcean]

Look at some of the brick materials in the starter content. They have shifting noise textures that do this kind of variation.