[DaleHCook]

Since most of what I'm ordering is 630V

In plastic caps I only buy 630 volt. Plastic caps don't care what the voltage is as long as it is below the rated voltage.

I do the same thing with 1 amp rectifiers in the 1N400x series. I only buy 1N4007 (1 kv) because they can be used in place of the lower voltage 1N400x rectifiers.

Note that I buy each value of plastic cap in a quantity of at least ten, and I buy 1N4007 100 at a time. I stock parts for a variety of electronic work.