Lon's statement to Milli saying, "I would like to sell you my comic book collection." is merely an invitation for a negotiation. It is not considered an offer because an offer would include the price and quantity of the good/s that will be sold. It may also include possible discounts and the date when the package will be received. Lon's statement can lead up to a negotiation wherein both parties will discuss their terms in order to form an agreement in the end.