Capacity to buy and sell is regulated by the general law concerning capacity to contract, and to transfer and acquire property:
Provided that where necessaries are sold and delivered to an infant, or minor, or to a person who by reason of mental incapacity or drunkenness is incompetent to contract, he or she must pay a reasonable price therefor.
Necessaries in this article mean goods suitable to the condition in life of such infant or minor or other person, and to his or her actual requirements at the time of the sale and delivery.