A pressure gauge installed on the fuel rail is the best way to check regulator. As long as your not sure this is your problem you may want to try one from the junk yard. Find a pick-n-pull as they are the cheapest and you get the advantage of being able to "practice" parts removal on a junk car before you work on your good car. Try and determine how a given car ended up in the junk yard. In other words a clean looking car with massive body damage would be a better car to pull parts from than a car with no visible damage. You know a wrecked car was probably running when it was wrecked. A clean wrecked car was probably running good. I would expect to pay $2.00 to $5.00 at the junk yard and on a good day they may give it to me for free.