Noida investment: Hidden costs and negotiation reality?

Since last year, I've been eyeing properties in Noida for investment, mainly 2/3 BHK units around PI Greater Noida. I'm based in Dubai, so site visits aren't easy, and I'm relying heavily on community insights. My main question is about negotiation. Builders like Brys Group, do they actually budge on price for a 2BHK around ₹80L-₹1Cr? Kitna realistically negotiate kar sakte hain, 5% or less? What are your experiences? Also, I'm worried about hidden charges closer to possession. Apart from stamp duty and registration, aur kya hidden expenses hote hain? For an investor, is construction-linked smarter than down payment? Need to manage cash flow remotely, any advice helpful.