Where do you live OP?
Looking at your profile and post history i get a feeling you are in India but offering to sell bitcoins in Australia, what the deal?
Haha. Maybe some kind of risky transaction. Buying large amount of BTC needs a security when it comes to the buyer right? Maybe he will tell his details when you message him and then hire some escrow to make your transaction more secure.
He has PM'd me his area and rates so i will see what he come back with when his online.
It sounds a little strange so i might do a little digging first but if it's a cash transaction meet up then i will have "security" with me, enough said on that.