Nova Tech US via Amazon offers the Nursal Rechargeable Tens Unit with 8 Pads for $36.99. Coupon code "6KMHODFN" cuts the price to $25.99. With free shipping, that's $44 off list and the lowest price we could find. It features 16 modes, 20 strength levels, and a built-in timer from 10 to 60 minutes.