The King Cobra started production in 1986 and was discontinued in 1992. the King Cobra returned to Colt's product line in 1994. It was dropped a second time in 1998 from Colt's product line.
check at: proofhouse.com/colt/index.html
If you call Colt, they will tell you.
50-500 usd
Proofhouse.com has Colt sn data.
Your best bet it to call Colt.
50-650 usd
about $600 to $900
The Colt King Cobra .357 is no longer in production. A King Cobra in excellent conditon could be worth as much as $1,500 depending on availibility in any given area.
$800 TO $1000
50-650 usd
50-550 usd