Echo Store via Amazon offers Prime members the Slicoo Screen Protector 3-Pack for iPhone 6 in Shining Pink, Matte, or Clear for $5.99. Coupon code "FN3EIEQJ" cuts the price to $3.50. With free shipping, that's the lowest total price we could find by $2. (Non-members can spend $35 to qualify for free shipping; otherwise, it starts at around $6.)

Also available for Prime members is the Slicoo Tempered Glass Screen Protector for iPhone 6 for $7.99 before the above coupon, $5.50 after. With free shipping, that's the lowest total price we could find by $3. (Non-members can spend $35 to qualify for free shipping; otherwise, it starts at around $6.)