See the link below for the Crosman 454 Owners Manual.
20-80 USD or so
25-50 dollars
Crosman 38 C combat In very good to excellent condition it is bluebooked between $75-$90. Add 20% for original box. Add 200%-400% for the chrome salesman sample pistol
Crosman is owned by Wellspring Capital Management. They are a privately owned company. They are located in the Leaver House in New York.
The Blue Book of Gun Values will give you a ball park. They don't show up often for sale.
Jiminez Arms
The CROSMAN 760 Powermaster started production in 1966 then went through 8 different changes and ended in 1991
Between $75-$100 is a common price today.
Your 38C Combat is a replica of a S&W 38. There were 2 variations made. It was manufactured sometime between 1973 and 1981. The value can not be determined because you have not stated the condition of the pistol.
Swiss Arms, UTG, BSA, Daisy and Crosman
It most likely refers to a pistol by Kahr Arms.