Plot sale - na - is the seller genuine?

This is reg. a farm land in hebballi/ shivalli. The firm selling the plots is named SS developers. It is located in New cotton market. They take for a plot visit. Asked to pay advance of 25000/- per plot. Total cost of one 30*40 is 5 Lac. He asked to the adv for development charges, he will register the land after 4 years or so. Remaining amount needs to be paid monthly starting August 2019. He has given some non-judiciary agreement papers . Taken my signatures wherever needed. Could anyone please help me if this guy is genuine or fraud . Awaiting your reply