Thousandshores via Amazon offers the Dr.Meter pH Meter Pen Tester for $13.99. Coupon code "DRZ4GFLP" drops it to $9.99. With free shipping for Prime members, that's $16 off list, tied with our mention from two weeks ago, and the lowest price we could find. It includes a carrying case and small screwdriver for calibration. Deal ends November 20.