Aha, the joy of seeing The Greek Anthology here on a Friday! I don't have a copy of that (because Loeb books are expensive, even used, but full text is here: https://archive.org/stream/greekanthology01newyuoft/greekant...) but for our Ancient Greek II class they had us buy A Hellenistic Anthology (https://www.amazon.com/Hellenistic-Anthology-Cambridge-Greek...), which is an abridged version with a ton (2/3 of the book) of commentary to help you along.

Although this book has 12 pages of selected epigrams, if you are like me, after some years the only one that stays in memory will be a dialogue (number 31), between a prostitute a a prospective client, using natural, everyday speech. This surely must be the earliest such written transaction.