Heavy deposit or lease for 1bhk in Navi mumbai,owner asking 15 lakhs.

The property is 5-7 year old,owner is asking us to pay 15 l upfront thereafter I have to only pay maintainence and utility bill for 3 years . 1.What if he does not return money after 3 years,Is there law specific to lease ? 2.I do have to make documents from court ,what are things I should look for ? 3.My mother and I have LIC policy and thinking of taking loan on it,as we hardly made anything on LIC,some bonus gets accumilated which we will recieve after 7-8 years. 4.The interest on LIC is around 8 or 9% (1lakhs per year plus 60 k maintainence).so my house costing would be 13-14k per month) 5.If I want on rent same rent , have to pay 32k monthly. Please help me with yours views,I have directly offered him 10 lakhs upfront ,he will come down to 12 I guess. For information I asked him what will he do ,he told us he will further arrange 5-10 lakhs and give downpayemnt for other flat ,which he will rent it . Is it legit . Thakyou for your suggestion and please share your experiences.