Amazon offers Prime members the Snark String Instrument Clip-On Guitar Tuner in Blue, model no. SN-1, or Black, model no. SN-6, for $8.99 with free shipping. (Non-members can spend $35 or more; otherwise shipping adds $5.07.) That's the lowest total price we could find by a buck. It features 360-degree rotation, tap tempo metronome, and a high sensitivity vibration sensor. Deal ends December 23.