Knife Country USA offers the UZI Defender Tactical Pen with Glassbreaker in Gunmetal, model no. UZI-TACPEN6-GM, for $17.49. Coupon code "Freedom" cuts it to $15.74. With free shipping, that's the lowest total price we could find by $4. It's constructed of aircraft aluminum and features a cuff key and glassbreaker.
Of note, All Natural Industries via Amazon offers the Uzi Defender Tactical Pen, model no. UZI-TACPEN3-GM, for $14.47 plus $4.21 for shipping. This pen includes the cuff key, but instead of the glassbreaker, has a DNA catcher.