Selling a house

And now for some more personal news: I am trying to sell my house. Or, more accurately, WE are trying to sell OUR house, there being two of us; my husband and me.
We first put it 'on the market' in June of 2011.  Within 3 days we thought we had a buyer. She (the potential buyer) assured the Real Estate agent that she had a buyer for her house and was anxious to move into the town where we lived.  She inspected our property at length, then brought along a builder to 'check it out'.  Next came a plumber and then her best friend.  Everyone "loved it" and we (and the R.E.agent) felt that we had made a quick and successful sale.
Off we went to Queensland to look at a house that we had discovered on the Internet. While we were inspecting this house and almost ready to commit to buying it, we phoned our agent to check that all was going ahead with the sale of our house as planned. Unfortunately the sale of the potential buyer's property had "fallen through" and the deal was off.
Over a year, and several more (fruitless) "inspections" and another R.E.agent later, we took the house out of the agent's hands and put it up for sale by ourselves, thinking that, with no commission to have to pay to an agent, we would be better off and, as it seemd there were no potential buyers in the offing, we may as well just play the waiting game on our own.
Two days after we relieved the agent of our property, he phoned to say he had someone wishing to inspect our home.
What to do?
This person came and inspected the property on behalf of his mother, who lives two states away.  He liked our house, took videos to send to his mother and then we had the mother's partner on the phone asking if he could come and see our place.
He is due to arrive in 3 days' time.  We are trying not to be too hopeful, but have found ourselves contemplating properties in Queensland, from details on the Internet.
We have not replied to the agent's phone message. Is that OK?