As in the case of considerations generally, the consideration for keeping the offer open must be that contemplated by the parties.1 An option to take such part of a certain quantity as the vendee may choose, is without consideration, although subsequently he orders and pays for a part thereof.2 An offer to sell a large quantity of goods or any part thereof, is not rendered irrevocable as being an offer for value by ordering a part thereof.3 A gratuitous promise to leave an offer open can not be converted into an offer for value by the voluntary act of the offeree in incurring expenses in reliance on such offer if there is no provision in such offer requiring him to incur such expenses.4 If A makes an offer to B, not for value, the fact that B incurs expense in attempting to resell such property;5 or the fact that he buys property to enable him to perform in anticipation of accepting such offer,6 does not make A's offer an irrevocable offer for value.

An option which purports to be given in consideration of a certain sum, which sum is never, in fact, paid, is not given upon valuable consideration,7 at least, in jurisdictions in which the recital of a consideration is not conclusive.