Amrapali Leisure Valley: negotiating final price, need advice

Amrapali Leisure Valley mein ek 2BHK dekh raha hu, kids have moved out, ab chhota ghar chahiye. Builder se negotiate kitna kar sakte hain? Base price pe kitna discount milta hai usually Noida mein? Aur all-in cost mein kya kya include hota hai – stamp duty, registration ke alawa aur kya hidden charges hote hain? Investwell Realty ke projects mein kya experience hai logo ka?