Copper is a monumental metal that will last for lifetimes and is an ideal material for your through-wall flashing. York uses copper that is 90% recycled and offer a life of the wall warranty on all copper embedded flashings, so there will be zero life cycle costs.
Rubberized asphalt membranes are used as air barriers, through-wall flashings, waterproofng and window and door tapes. This flexible flashings cold flow capability allows them to seal around nail heads and punctures.
PVC flashing membranes are an inexpensive short term flashing option.