Well, they stopped producing the Twin Otter in 1988, and the new-build Viking ones (of which there would only be a handful in existence) have big price tags.
Similarly, the 228 stopped series production in the '90s, with a handful of new-build "ng"s being built in the mid '10s.
You friend is going to have to alter his perceptions of aircraft age, there are almost no shiny new aircraft in that sector.