Sears offers the ZAGG invisibleSHIELD Glass for iPhone 5/5s/5c for $20.99. Plus, Shop Your Way Rewards members will receive about $30 in SYWR Credit. (Not a member? It's free to join.) Opt for in-store pickup to avoid the $5.99 shipping charge. Assuming you'll use the credit, that's the lowest total price we could find by $27. It features oil-resistant, fortified tempered glass.
Of note, Shop Your Way Max members are eligible for free shipping.