Hi,
Isinya is the right place to invest now.
I am aware of the area between Kisaju and Isinya and that is the only one I can say something about.
Near Kisaju, 1 acre on the road goes for around 4M; I am currently in the process of buying (by instalments - with Daykio - 0.5 acre 1.3 km from the road, at 1.0 M).
Beecause the distance from Kisaju to Isinya is not significant, I believe that the price is roughly the same as Isinya. However, in Isinya town, it must be more expensive.
The best.