Having run an Envision full time since 1998 and still having the original bail arms and plastic bails, I would say that unless you damaged them somehow, they should need nothing more than a thorough cleaning and a few drops of sewing machine oil to restore them to good working order. Simply put, they are built like tank parts and don't wear out easily.
If they are damaged and require replacement, my educated guess is that the parts were custom manufactured for the Envision and you will need to bite the bullet and pay the piper.