A few hundred to a few thousand USD, depending on EXACTLY what you have.
Impossible to answer without a detailed description of all markings, features, condition, box, accessories, etc..
value depends on overall condition. go to: coltforum.com and ask.....
You will have to call Colt with the sn to find out.
The gun sold new for $225.00, on todays market they are worth whatever someone will pay. Not really a collector gu but in excellant shape $350.00...
I work as a weapon appraiser in the state of Iowa. I have seen a few of these pistols in my time and they usually go for about 1,000,000$ depending on the condition.