Alexa, who is 17 years old, is a rare stamp collector who resides in Miami, Florida. She is always looking for rare stamps to add to her collection. She joined a rare stamp collectors' group on Facebook where she met another member name Siri, a 21-year-old who lives in Los Angeles, California. Siri posted a rare stamp for sale, an 1851 Franklin 1 blue stamp worth $750. Alexa had been searching for months for this one stamp. She decided that she would buy it for her 18^th birthday. Alexa contacted Siri and they chatted over Facebook messenger about the stamp. Siri agreed, through Facebook messenger, to sell Alexa the stamp for $750.

At 12:01 a.m. (Miami, Florida time), on the day of her birthday, Alexa sent Siri a CashApp payment for $750. The next morning, before Alexa could confirm that Siri had received the payment, she saw another member of the Facebook group selling the same stamp for $300 less. Alexa immediately contacted Siri and demanded that she refund $300 of her payment or cancel the deal altogether. Siri said no and told Alexa that she had already mailed the stamp to her and that the deal was final. Since then, Alexa has been unable to make contact with Siri.

Alexa comes to you for legal advice. She has received the stamp and was able to get Siri's address from the envelope. Alexa wants to return the stamp and get her money back. In the alternative, she will keep the stamp, but she wants $300 of her money back. How would you advise her?