I think there are two versions one with f/2.8 lens and other with f/1.7 lens. The former should be cheaper. If you search B&S section you could find the canonet going for something betwenn 100 - 200 (with flash).
Really hard to get GL19. This one has 45mm f/1.9 lens and as you said fairly rare. I have not see one sold in B&S recently. I guess since these were not pretty popular model and the market for fixed lens rangefinder is not very hot, you might land one for something in US$100 range. I have a canonet GL17 (with 40mm f/1.7 lens) and I paid 120 for camera and canonet flash.