If you are selling equipment from demolition sites you have an added bugaboo concerning the proprietary nature of the equipment.
Remember when Murray Demolition had a contract to demolish a Celanese plant in Edmonton and a company was buying the equipment and shipping it back to Iran and building a vinyl acetate plant which would have competed with Celanese. Celanese accused them of divulging proprietary information about their process line. I think that case made it all the way up to the Canadian Supreme Court.
Who can forget the guy who owned the salvage yard in Pocatello, Idaho and bought a nuclear reactor.? He had a sales contract with the Chinese but they wanted an operations manual and he didn't have one. So he sent an e-mail to BNFL in the UK asking for one. They alerted the UK government who faxed the FBI. The US government had to buy it back from the guy for some kind of crazy $$$