My money, my headache now

₹6500 per sqft was the rate I was quoted for a 3BHK in an Under Construction project near Sector 16C just 18 months ago. Now it's pushing ₹8000, almost 23% up. I work in real estate, but buying for myself is a whole different ballgame. This specific builder, big in Noida Extension, kept delaying their RERA approval, pushing back possession dates too. Now they're justifying the hike with 'material costs' and 'increased demand'. Honestly, I'm stuck. Is this price trend sustainable or are they just playing games? Should I jump in now, or wait another 6-12 months hoping for a correction? What are people seeing in other 'Under Construction' projects? Any advice on whether to buy or hold?