The gravy train just keeps on rolling for thrifty Android games. In addition to the dozens of titles on sale from other developers, retro specialist DotEmu has put all three of its Android titles on sale. You can pick up classic platformer Another World for $1 (75% off), shooter legend R-Type for a dollar (40% off), and shoot-em-up anthology Raiden Legacy for three bucks (40% off).
All three are solid games with 4+ stars on Google Play, well worth it if you're a fan of the original games or just the genres in question. Raiden Legacy in particular offers a lot of bang for your buck, with four top-down shooters in the same package.