Wow, no way I'd pay that much for a Gen 1.
The most expensive older Glock I purchased is my Gen 2 C serial number G24. It is in excellent condition, maybe a couple magazines fired, still clean with the factory copper lube. I haven't fired it. I wanted a second Gen 2 G24 in case my old A serial G24 ever broke. I gave $550 for it.
GLOCK Certified Armorer, GSSF member, NRA Life Member
Currently: 17x2, 17L, 19x2, 20x2, 22, 23x6, 24x2, 34x2, 35+1, AA LE 17-22 on G31 frame, Olympic Arms K9-GL
Have owned: 21, 26, 27, 29, 30, 31, 32, 33, 36