Where to buy correct alternator for a 1969 340 swinger non a/c car

It's such a shame that cores are a problem these days. 10 years ago when I was retiring and selling off most of my inventory, I tried to find a core buyer for alternators and starters. Couldn't find a buyer anywhere close and shipping was too expensive for those in other states. I must have scrapped 60-70 alternators and about the same in starters. There were lots of original ones with date codes and correct pulleys.