modular setup will likely be either in 2x2 grid, or 3x3 grid.
for 120" setup, that would be 4x60" panels, or 9x40" panels.
for 150" setup, that would be 4x75" panels, or 9x50" panels.
the costly part, would likely to be how to make the panel gaps/modular grid lines, invisible such that the images and motions would look smooth and pleasurable.
the other costly part, will be the panel controller... that splits a single source to 4 or 9 different panels/modular displays to do their part of job.