Renting's over: My first investor steps in Gurgaon

Visited Ganga Group's project in Sector 107 last weekend. Fed up of renting, finally looking to invest in a 3BHK on SPR. Do builders really negotiate much on listed prices? Matlab, kitna discount expect kar sakte hain? And what about hidden charges like PLC and maintenance deposit? Aur kya dekhna chahiye before signing?