Here is a magnificent South Korea collection of what appears to be all MINT NEVER HINGED starting in 1960 and going up to the end of 2008. The stamps are over 95% complete for the period, with mostly the definitives missing. The souvenir sheets start around 1973 (there are a few earlier) and that is over 95% complete as well. Catalog value is just too much to calculate, but well into the thousands. As an extra bonus, there is a North Korea stock book with about 50 sheets.