Pune investors: How to tackle hidden charges in Mamurdi?

Since January I've been shortlisting 3BHKs in Mamurdi, planning to upgrade from my Baner 2BHK. Builders like Godiva Promoters Llp quote one price pre-launch, but then possession tak aate aate, hidden charges poora budget hila dete hain. PLC, floor-rise, electrical infra, society formation... it's never upfront. How much can one realistically negotiate these down? For an investor, which is smarter: construction-linked payment plan or a larger down payment? My current home loan chal raha hai, so cash flow matters for ROI. Is there a way to force builders to give a full 'all-in' cost breakdown early? Anyone faced this in Mamurdi or Pimple Saudagar recently?