Upgrading from 2BHK in Pune – real costs, real negotiations?

My current 2BHK in Baner feels too small now, thinking of upgrading to a 3BHK or maybe a villa near Narveer Tanaji Wadi. Builders like Harmony Group often bolte hain prices fixed hain, but does negotiation actually work in Pune? Kitna discount expect kar sakte hain? Also, what's the real all-in cost? Beyond agreement value, registration, stamp duty, there are so many hidden charges like PLC ya parking. What's the best way to figure out the final amount before signing, so no last-minute surprises?