Sir,
You are a kind hearted person and have money in your pocket. The Supplier knows it very well and that is why he wants to cheat you with the money you have with you. The reasons are transparent which you cannot see with your eyes.
1, He wants money in cash. In case of dispute it is not possible for you to prove from where your brought this amount of Rs.3.00 lakh.
2. He would never take any cheque or transfer in his account.
3, Rent agreement is not a collateral.
4. He would not give you post dated cheque.
5, You have no licence of money lending.
6. He would not have the permanent address and property in his name.
7. He would never give you original title documents of his property.
My sincere opinion is to stay away from the supplier and save your hard earned money failing which you will be spending your rest of the life to visit courts and invites unwanted worries for ever and loose the relation as well.
Take a reverse gear in all possible means.
Even if, still you want to help him, you can go ahead. Good luck.