The way to prevent ESD damage from happening is very simple. Three passive components are required to prevent static damage to the RS-485 to UART transceiver chips. The transceiver chips probably cost them about 2 dollars per chip at the quanitity they order them. The three passive components needed are two resistor and a TVS Diode. All these components are pretty cheap and will cost about 60 cents per port or $13 per V5. Also the how to guide for preventing static damage to the chips is like the first result on google. Linked here: http://www.ti.com/lit/ug/tiduai4/tiduai4.pdf