Interarms PPK/S? I don't think S&W made any.
Caliber would determine value. Interarms pistols and their parts are worth less than the German originals due to quality difference, but a PPK/S slide in 380 would be a couple of hundred dollars, pictures would help there, and a PPK/S slide in .22 would be worth a bit more, say two hundred fifty. A .32 slide would be less common but of very little value unless someone had a broken one.
Recoil spring and grips aren't worth much. $20 for the spring, maybe $30 for the grips if they're nice.
Correct me if I'm wrong, ladies and gents!