The value is based on condition , condition and condition. A rusty junker might bring $150 while a pristine as-new with the box and all papers might bring $750 from a motivated buyer. It all depends.
made about 1976
100-1000 USD
50-475 usd
Your colt agent was made in 1964.
Need serial number. Try proofhouse.com
You need to call Colt
50-500 usd
Serial Number is 91953 Colt - 32 Police CTG Postive
No such sn in published references. You will have to call Colt. I have one W26XXX it was made between 1984-86
You must provide the serial number or call Colt and ask.
To my knowledge no .38 Special was ever rated for plus ammo. While the gun may not explode you may damage it or cause extensive wear.
Made in 1978.
Need serial number to answer or go to proofhouse.com to look up.