In those rare instances where I resign myself that there's just not enough light to shoot without a flash despite that wonderful f1.4 lens on a leaf-shutter rangefinder that can be handheld to 1/15th or 1/8th
The flash I use and would heartily recommend would be the Vivitar 252. This flash goes with the Lynx 14e like peanut butter goes with jelly, like bacon goes with eggs, bread goes with butter. (You get the pic) They pop up pretty regularly on eBay. Couple things I like about it - it's compact, reasonably powerful, cheap-cheap-cheap, rugged, and it's vertical (Vertical always looks cooler on a rf camera. Don't ask me why.) It also has a little compartment where the PC cord, which is a hardwired part of the flash, can be tucked away. It's a thrystor model but it has a dial that can be illuminated by pressing a button that lights up a pie-grid for the proper fstop for the distance and film speed you're using. Nice... Because of this, I leave it on manual since the chart faces you and is easy to read in any lighting condition, including complete darkness. Nothing beats manual for proper flash exposure, and this unit makes it easy with a simple feature I wish more flash units would have. It's also hotshoe capable (just leave its built-in PC cable tucked away in its compartment). ISO 100 Guide Number = 64. Operates On 2 AA Batteries.
Cameta Camera has one for $15.00 used (they're all used) Here:
http://secure.cameta.com/index.cfm?fa=display.showused&letter=V&sort=1
Cameta gives you a six month warranty, I think. Can't beat that deal with a stick.
Do note, however, that my Konica Auto S3 doesn't like this flash for some reason. So I dare not try it with other cameras. Works perfectly fine on the Lynx 14e. Might have something to do with voltage. Dunno.