We need much more info:
Blued, nickel, satin stainless, or mirror bright stainless?
Barrel length, 2 1/2", 4", 6", 8" or a rare 3"?
Caliber .357 or .38 Special?
Original wood Colt Target grips, version of Target grip?
Percent of original finish?
Any rust, pitting, or scratching?
We can tell you when it was made if you post the serial number, or you can call Colt and they'll tell you over the phone.
IN GENERAL, a blued Python in 95% condition with original grips starts around $800 and up.