The value in used Concrete Batch Plants is fully erected as-is where-is.  Concrete Batch Plants are grandfathered into the original building permit restrictions. 

When a plant is removed from a site, it is basically scrap iron because of the unknown of the new site location building dept restrictions.  In order to move forward, you will need to get a site soils report and hire a local structural engineer to confirm the existing plant structure will meet the current seismic and hurricane wind loads.  Typically about $25k-$50k. 

Potential upgrades to meet current Building Codes is $90k - $200k if possible.