Do you mean the "Detective Special"? I think it's a 2" barrel snubby in .38 special? Value depends on condition (especially if it has rust). How much use and wear, etc. I recall the Detective Special was somewhat collectable (?). Is it for shooting or collecting? If a shooter, try it out and check tightness of fitting, look for timing problems (spitting at the forcing cone). Check for cylinder wobble or end shake.
If it's really nice, it might be worth $300 - $350? If it's a collectable, maybe a shade higher. If it's not nice, ain't worth much.