Forget about walking.  "Walking distance" is not a concept which exists in Doha.  For most of the year it's too hot and even when it's cool enough it isn't safe to cross the main roads.  Housing in Al Gharrafa and to the west of  the North Road is a bit cheaper because it's further out of town but still handy for Compass.  West Bay is also convenient but probably more expensive.  There are also school buses.