Sohna Road pe 3BHK: Best deal kaise milegi?

Currently in a 2BHK in Sector 43, thinking of upgrading to a 3BHK on Sohna Road. Budget is around 2.5 Cr. Lion Infra Developers ke naye projects dekh raha hoon, but secondary market mein bhi kuch ache options mil rahe hain. Mera main doubt hai ki resale properties mein negotiation ka scope zyada hota hai kya? Aur builder se direct deal karna better hai ya broker ke through jaana for maximum discount? Already home loan hai, all-in cost bahut matter karta hai. Aap log kya suggest karte ho?