The deal is available until September 27, so there's plenty of time to decide whether or not you want an iPhone SE, although there are a couple of things that you might want to know. First off, the deal seems to be available in-store only, so you won't find it online.
Secondly, in order to qualify for the deal, you have to activate a new line of service on any monthly plan and purchase a $30 or larger refill card. Even so, getting the iPhone SE for just $49.99 is pretty amazing considering that many carriers are still selling it for $350 outright.
Last but not least, the activation of a new line and the $30 or larger refill card must be purchased in the same transaction in order to be able to buy the iPhone SE for just $49.99. Happy shopping!