It is a bit of detective work to find suitable rubber replacement from other cars. Your best bet is to take a small piece to a self serve wrecking yard and see if anything matches. Years ago a late 70's Plymouth Sapporo door molding fit my '65 Plymouth Belvedere hard top and the late 90's Mazda MPV was a good donor for my '64 Studebaker.

That said the JY prices are getting crazy. Not that long ago I had the ability to hit two self serve yards within a mile of each other. One charged a flat rate of $3 for a whole door rubber seal. The other yard charges by the foot and I believe the price is now $2 per foot! For some doors that is pushing $25 for used rubber! I sure wish that one yard hadn't closed as it had been around since the late 1920's. But an aging owner, regulations and healthcare cost shut them down.