Meet Roadie: an automatic guitar tuner with a mobile app that provide you with an accurate performance. Just connect it to the peg of your instrument, strum the string, and let the device do the rest. Roadie comes with 8 tunings for guitars, but you can customize it. Roadie can tune various string instruments, including electric, acoustic, classical, and steel guitars, 7 and 12-string guitars, banjos, and ukuleles.
Roadie lets you know when your strings need to be replaced. The app is compatible with iOS and Android devices. Roadie costs under $100.