Joe was looking through Facebook one morning and saw a post from Super Electronics stating: "New iPhone X 50% off, today only!". Joe needed a new phone, so immediately left home to walk to the Super Electronics down the street. He stopped a vending machine to put in $2 for a bottle of pop. Posted on the machine was a sign promising $50 to anyone who returned a lost dog. As Joe arrived at the store, he got a phone call from Harry. Harry said he was just speaking with the local YMCA, which offered to name a new building after him if he donated $20,000. Being in a generous mood, when Harry heard Joe was walking, Harry promised Joe he would give Joe his old car when he bought a new one in a month. In the store, Joe discovered all the iPhone X's were already sold. However, the store was willing to take payment now and provide Joe with his phone as soon as they were in stock again. Joe said he wanted a silver coloured phone with 128GB of memory. He paid with his credit card. On his way home, Joe stopped at a restaurant for lunch. Looking at the menu, he saw that the fish special was available at market price. He ordered it.

From this scenario, please identify:

An invitation to treat (as opposed to an offer).

An example of a unilateral contract.

A warranty (as opposed to a condition).