It is important to get multiple bids when determining your modular home costs. Another thing to keep in mind is that you should not necessarily choose your contractors because they are the cheapest. You must check with references, view previous work they have done, verify that they are insured and licensed to work in your city. I met with my foundation contractor at a job site he was working on and was so impressed that I chose him even though he was the highest of my three bidders. I could have saved a couple of thousand dollars with someone else but I doubt it would have been worth it.
If you do not feel that you have the time or expertise to manage the contractors involved, many modular home builders will act as your general contractor for a fee. This may be the route to choose if you do not have time to meet with all of your contractors at the jobsite.
Finally, keep in mind that you should pad your budget by about 20% for unforeseen things. Even though the site work is minimal on a modular home versus a site built home, you must be prepared for contingencies. Weather delays can cost you more interest on your construction loan, excavation costs can rise if it is a difficult jobsite, etc. Every construction job has its problems, so be prepared with extra money in the budget to be able to handle these issues as they arise. Tim Montey