The implied warranty of merchantability ensures that a product is adequate for the purpose that the seller claims it will serve. This warranty only applies if the seller is a merchant. Therefore, if someone buys something at your garage sale that turns out to be broken, the warranty would not apply because you are not a merchant. The implied warranty of fitness for a particular purpose only applies if the seller knows that the buyer has a particular purpose in mind. For example, if you request basketball shoes for your daughter and the seller provides ballet shoes, this would be a breach of the implied warranty of fitness for a particular purpose.
State law determines how long an implied warranty lasts.
If a product breaks after the manufacturer's warranty period, the buyer may still be able to get relief. Many stores offer their own full warranties, although the length of this warranty may be shorter than the manufacturer's warranty period. In addition, some credit cards may double a manufacturer's warranty for up to one year if the product was purchased with the card. You should not allow yourself to be pressured into buying an extended warranty or service contract. Instead, you should carefully consider whether the extra benefits are worth the money.