the new Xenar 150 5.6, wow! I ask myself thou why don´t just use a 70ies Xenar 4.5? do the coatings make such a difference in this simple lens design?
the Xenar 3.5 is interesting in it´s drawing and so is the tessar 165, both are well under 100 (Leica shop vienna has a 165 f2.7 in focus mount for 120!)so it´s a cheap fun to try those lenses. thats what I love about LF!
fred
My 150mm f5.6 Xenar was less than 100

I bought it about 3 months ago from a UK based APUG/LFPI member for £100, it's still looks new. Xenar's were only ever single coated so despite being made around 2000 it's like the 70's versions.
Some where I should still have a 60's perhaps earlier 150mm f4.5 Xenar in a broken shutter, but I've not seen it since the late 80's. The early coatings weren't as good as the later Xenars or even my early 50's CZJ 150mm f4.5 Tessar.
The trade off with Xenar's (& Tessar's) is increased size and weight with the faster versions, and a decrease in optical quality, the design gives it's best performance stopped well down. This was why the Xenotar design was introduced for the fast Schneider lenses.
Robb Scharetg's list is interesting but many of the faster lens won't cover 5x4, so in reality for 5x4 the fastest lenses that are easy to find are the Xenotar and the Aero Ektar.
Ian