FYI, Undiluted green is often scarce around here too. I've taken to ordering several gallons at a time from Rock Auto. It's less than $8 per gal for FVP or $969 for Zerex. Even with shipping it's cheaper than the local auto parts stores. Every color of the rainbow.

https://www.rockauto.com/en/tools/cooling+system,fluid+/+chemical,coolant+/+antifreeze,11393


1950 Chevrolet 3100 (Ol' Roy)

1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)