As you are working your way through this free class, studying and reflecting upon Epictetus' Enchiridion, you'll want to have some copy of the text for yourself. Of course, you'll also see the text in each of the lecture videos - in Greek and English - but it's important to have your own copy that you can carry around with you, mark up and write in, dog-ear - whatever it is you like to do with texts.
The translation of the Enchiridion that I used for creating the videos is a less recent one, by W.A. Oldfather, and the version I particularly like - for my own reading, study, and research work - is the Loeb Library edition, which has the Greek text and English translation on facing pages. The main reason I prefer this edition is simply that it does have the Greek - there's nothing particularly great about Oldfather's translation - so that if I wish, I can just read the text "straight", or if I'm reading the English and want to check the translation, I've got the Greek right there.
If you're interested in acquiring that version of the text, you can purchase it using these links. Buying one volume will set you back about $25 - and if you intend to go further than just the Enchiridion, you may as well get both volumes:
There are a number of other translations of the text available online, which you can download or access entirely for free using these links
If you want to purchase a copy of the texts, there's quite a few available - and if you're doing that, you may as well get the Discourses along with the Enchiridion.
This is also, of course, a book that you can quite often find in used book stores or in your local library.