Style chooser

Good day to all. I am about to purchase a car. I've seen the car, checked by my dad's mechanic and all of us are happy to get the car. The problem is this. I am going to buy it for cash meaning no third party or bank or middleman or brokers involved.

The arrangement by the seller is such, i pay him a deposit and he'll give me a letter to state that he received money for the deposit. It will be written by himself and signed by him, me and 2 other witnesses with our names and NRIC numbers...