Now we know what you're thinking. The LG G2 isn't a cheap smartphone. You're right, but since not everyone wants to sacrifice specs and features to save a buck, the LG G2 is only $99 with a new 2-year contract from most carriers in the US. Making it one of the absolute best devices around for under $100.
You'll get a 5.2-inch 1080p HD display, quad-core processor, a stunning 13 megapixel camera on the back with image stabilization, and arguable one of the best smartphones from 2013 for only $99. You can't go wrong here, as long as you're willing to sign a contract. The same can be said about the Galaxy S4 from last year too.