Cash is King. I have used cash and also have paid with a cheque. I gave the seller a cheque for the full amount. We both waited a few days for the cheque to clear, then I picked up the pin.
Do not walk into the house alone with the cash, leave it secured in your ride. Do not make your self a target. What can happen and has happened with online used car sales, is that the item is not there and the criminal knows you will be bringing cash.