Are you absolutely sure you are required to test to 200 pounds per square inch rather than 20 pounds per square inch? 200 psi is high enough to blow the regulators and diaphragms out of normal static pressure stabilization equipment, and much of the city connected equipment, if it isn't isolated properly. Are you pressurizing a Commercial system? If so seek help from LICENSED plumber before you explode the system.
: What would be the best way to test PEX. Since I have to do this only once, what is the most economical way to apply 200 PSI to the system? and how?