My first home purchase in GN — what hidden costs should I watch out for?

Renting in Greater Noida has become ridiculous, honestly. My landlord just hiked the rent again and I'm finally taking the plunge to buy. Been looking at 2BHKs around Sector 120, seeing prices for Alpha Builtech projects near ₹70-80L. The EMI vs rent math finally makes sense. But man, the all-in cost is confusing. I'm worried about hidden charges that pop up late. Things like club membership, maintenance deposits, or even random 'development' fees – what's the actual total I should budget beyond the quoted price? Also, for under-construction, is a construction-linked payment plan truly smarter than a down payment scheme? Seems like builders push CLP, but I'm not sure if it always protects us from delays or unexpected costs. Any experiences or advice on these? Don't want any nasty surprises at possession.