Don't over look Canon LTM lenses, which offer to varying degrees a vintage lens signature and are affordable. Canons use odd filter sizes. The build is a notch below Leitz, but I prefer them to more modern line-up from Cosina Voigtlander.
The Cosina Voigtlander 35/2.5, 28/4 and 21/4 are compact lenses which are rangefinder coupled and very good performers, albeit with a modern lens signature. Compact is the operative word. Since on a Barnack body that is important. The build quality of the C/V lenses is astounding good for the cost.
For a more vintage lens signature either the Soviet Jupiter 12 or the Summaron 35/3.5 will do and are in my opinion affordable. The Summaron is a tourist lens, best used in daylight at f/5.6 to 11. The build of the Summaron is pure Leitz, which means excellent - but for the money the Soviet J-12 is definitely worth a try.
There is the rare LTM Summaron 35/2.8, which is even better, takes 39mm filters, but due to its rarity this lens is pricey for what it is. It is superbly superbly built, though. Compared to stratospherically priced Leitz Super Angulon - it may seem more reasonable - but these are still lenses for LTM users with very deep pockets and a inherited trust fund.
