Have you thought about other sources? Have you checked Mouser?
Yes, Mouser doesn't have them either...they list them, but they are discontinued. The only other film caps they have are Kema or something, and they are 5% tolerance and not 1% like the Panasonics. I don't think Mouser does $2.41 first class shipping like digikey either.
Could you share your application requirements with us and possibly explain why you think one dielectric would be better then another in your application?
I'm building a very high gain (60dB) photo preamp and the design specs the Panasonic caps. I wanted to stick with the spec'd caps to be safe, but there is another equivalent cap at digikey that you think would be equivalent I would try it. When I was searching digikey I didn't see any other 50V film caps at all besides the discontinued Panasonics.