Here is a very helpful article that will help you make smart decisions before you buy a used modular building, mobile office trailer or portable classroom. I wrote this for www.buyausedmodularbuilding.com in January 2015 - and it has helped people like you understand the most important things to look for when buying any type of modular building from a private owner or a reputable supplier.Read the full article here - Tips for Saving Money by Matt Banes, President of iModular.com.