There are 3 types of approval authority - BDA, BMRDA, DTCP.
BDA - Bangalore Development Authority (For Bangalore Urban)
BMRDA - Bangalore Metropolitan Rural Development Authority (for Bangalore Rural)
DTCP - District Town Country Planning (for outside Bangalore district)
BDA is the costliest one amoungst all of the approvals. Then BMRDA and finally, DTCP.
You are correct. Those sides are still under rural regions so BMRDA approved layout are there and in cheaper rates. When they will be under BBMP limit then per sq. feet of site will hike like double.
There are many advantages then disadvantages. Layouts approved by those approval authorities says that land having clear titles, clean papers, etc. They strictly maintain certain rules and regulations to form proper and genuine layouts like layout must have good wide roads, parks, enough space for greenery, etc.
By the way, how much they are asking per sq. feet in electronic city?
De Arch Estates