Hidden charges after possession in Sector 52, did I overpay?

Okay I'll be honest — just moved into my 2BHK in Sector 52 last month, possession was a headache. Prithvi Associates se liya tha. I thought I negotiated well for ₹78L, but then hidden charges like OC, maintenance advance, and PLC adjustment popped up. Total cost bohot upar chala gaya. Has anyone else felt ki initial price negotiation is pointless with all these last-minute add-ons? Kya realistically 5-7% se zyada negotiate kar sakte hain in Greater Noida?