I'm going to assume you have a KM100/AK40 cardioid capsule, since that likely for hihat.
Cost on the KM100 preamp was around $350 when they were available, and the AK 30, 40, or 45 series capsules to go with them ranged around $600-700.
Dealer cost on the mic would probably have been around $850-900.
They are sonically most close to a KM184 series mic, much more so than a KM84 which is becoming a very hot vintage mic these days. But real street value for original KM84s and KM85s is more like 700-800, though the guys who restore and sell them get between 900-1100 for them.
By the way, Restoring a KM84 to factory spec runs around $250-300. (I've had three KM84s and a KM85 re-done, they match very nicely! I prefer the KM85 on hat myself...)
The original, Telefunken KM54s, sell for around $2000 - 2500 each these days with outboard power supply.
Hope this helps!
Jim