Gen 3 or 4?
that is a fair price for a used but in good shape Glock 19 in either Gen at least by 2019 numbers in 2020 while they may be unobtainium it may be better then fair
if it has a lot of holster wear you could a year ago have a G19 Gen 3 for 500 and a gen 5 was 550
I like the G19 but shoot it better when it has Mag pinki extensions I wear XXL gloves
https://www.amazon.com/Pachmayr-Grip-Extender-Glock-Full/dp/B07BLH37JWany idea how much use it has seen Gen 3 replace the recoil spring at 3K rounds and Gen 4&5 5K rounds the Gen 3 spring is about 10 dollars the 4&5 springs are about 25-30