I am looking for a place near to islamabad to either build or buy a 2 to 3 bedroom house far from city or near to conservation area with natural beauty.
Your best bet is either Bani Gala or D-12. Both are surrounded by nature. D-12 is a proper CDA sector so the prices are very high. A 4 marla plot here will cost you the same as a 1 kanal plot in Bani Gala.
I second above comments.
To elaborate further the land between upper banigala to cda botanical garden parkland is a good beautiful place to explore for genuine buyers for a nice retreat. Its the other side of park view city across the green hills. Upper banigala location is very good because its accessible from main muree road through korang road under 10 minutes and completely avoids/skips going through all the congested banigala village. Check google maps.
Disclaimer: i have a stake in upper banigala but not involved in any kind of trading