Even the items I regarded (until now!) as "cooking models" are apparently getting big money, such as the 35mm Summarons and 90mm Elmarits.
A lot of lenses are getting a new life. The Summaron because of its size and lens such as the 90mm Elmarit M because it is now recognised as one of Leica's nicest rendering optic's. But you should look at 'completed listings', and make sure you are looking at the correct part of the world, there is an overheated market in Japan and the Far East which doesn't reflect a realistic price in Europe for example.