Information is power. Since it would need to be moved, you need to be able to refer the prospective buyers to house moving companies. While you are interviewing the house moving companies, get some unofficial "ballpark" estimates for the lift, the move (per mile) and the setup. . There are likely to be substantial set up costs. - Permits, Foundation, garage, hookups, testing systems, certificate of occupancy agreements, etc. etc. -
There are a few people who may want to take this kind of project on. They are usually investors who are in business to make a considerable profit. The modular will have to be nearly free for the house moving investor to shoulder all of the other costs and risks to the project.
Since you have a high appraisal for the property, would you gain more financially by donating the building to a non-profit (example only - not a specific endorsement ) such as Habitat for Humanity. And then possibly taking a charitable deduction for the value on your taxes?
Organizations of that type occasionally have land donated and labor donated, so a project that might not make sense in the private sector might make sense in the non-profit sector.