You must be joking. There are 10s of 100s of companies selling these capacitors. I myself have started using oil filled MPP capacitors past 2 years both in my amplifier and crossover. They are equal to or sometimes better than the so called audiophile capacitors. You need to search hard to find the right brand and the end result will be highly rewarding both quality and cost wise.
My 2 paise.
PS: I have many of the so called audiophile grade capacitors gathering dust after apples to apples comparison with the oil filled capacitors, i stopped using them. Any one interested to get them, please DM me.