Anywhere from 100 to multiple thousnands of USD
plenty of difference the ppks is a shortened version of the walther pp - it is not a ppk - thanks to stupid govt regulations
Take it to a professional who specializes in air weapons.
100-1000 USD depending on specifics
100-1000 without more information.
100-1000 or so
There were two companies known as Interarms. The first was an importer/exporter, formed in 1953. They did not manufacture firearms. The second - and current - Interarms is a subsidiary of Hi Standard, and does not manufacture a PPK or PPK/S pistol. If what you have is actually a Walther PPK/S, value could range anywhere from $300 - $800, depending on specifics.
The PPK/s is a PP with a PPK slide.
1969-1984
no published sn data.
The Walther PPKS with serial number 060373 was produced in 1971. The PPKS is a variant of the PPK designed for the American market, and its production began in the early 1970s. Specific serial numbers can often provide a more precise date if cross-referenced with production records.
Someone on the P38forum.com might have access to that kind of data.
You might have better luck on P38forum.com