Head to your local M·A·C store on Saturday, April 18 or Sunday, April 19 and get a shade matched free travel-sized foundation This 0.5oz freebie is valued at $19.50 value! You can also get a free cosmetic bag with any $70 purchase, but this part is fully optional.
I can't find anything on their site about this, but there's an Eventbrite page for this deal. It also contains a full list of participating stores.