Pre-launch deals actually save money?

Budget finalised, loan pre-approved — now stuck on which sector. Shanders Group ka ek project Chansandra mein dekh raha hoon. Pre-launch offers mein kya sach mein koi fayda hota hai ya bas hype hai? Builders bolte hain discount hai, but later open market mein same price mil jaati hai kya? Construction-linked payment plan better hai ya down payment option? Honestly, ab samajh nahi aa raha.