If you want to replace the non-polarized electrolytics with the same type Parts express seems to be the best source. Most people, me included replace them with poly film type cap's. Parts Express has the Dayton line which are cheap and pretty good.
There are not many vintage speakers, from the the 1950's and 1960's, and into the early 1970's that warrant up-scale crossover Cap's. The Daytons, Mundorf MCap EVO's, and Axon Truecaps are good. I would not spend any more. Because they are cheap replace the resistors with non inductive Mills, or Vishay Mills resistors. My experience with my Wharfdale W35 recapped with Daytons, and the Polk Monitor 10B recapped with Axon, and Sonicraft II Cap's it does make a huge improvement in the sound