why the house prices are relatively cheaper in the Sambro and Ketch Harbour area, in southern Nova Scotia?

Sambro and Ketch Harbour are two communities that have been slow to be "gentrified." Like many of the smaller communities along the shore, they used to be fishing villages, and locally there is still a bit of a snobbishness about that area. Also, the highway leading into these communities is not as good as some other coastal communities. However, they are both beautiful areas and you can still get some bargains. Anyplace within an hour drive of Halifax that is on the shore is getting snapped up fast!

I pretty much agree with the other answer. There was a time when anyplace off the the peninsula was pretty much downscale compared to peninsular Halifax. Twenty years ago folks would have a cottage at Chester etc. but not too many people commuted in from the south shore. The Armdale Rotary is such a pain. Because the Chester area has been cottage country forever, that's where the upscale housing went when the roads improved. Sambro and Ketch Harbour have always been insular fishing communities, not bedroom communites until now.