Bahria enclave sector p 8 marla

Salam. I am interested in buying plot in bahria enclave sector p 8 marla. They were launched for 36 lakh and now agents are selling on profit between 2 to 4 lakh depending on location. Moreove on the map retaining walls are also there. What do they mean buy retaining walls? Is this investment good? Which streets are recommended as one agent said street 9 is bad.