First, do you own the land ? Then think about the "stage of completion". Do you want it completely finished ? If so, do you want upscale amenities such as hardwood floors, granite counter tops, etc.
There is a modular home builder in Lexington,MS. Some names to investigate online are Safeway, New Era, Carolina Building Solutions, and Genesis.
A ball park idea on price is to estimate the coast of'stick built" and then realize that modular will cost more.