Newegg offers the Symantec Norton Security Deluxe 5-User 1-Year for Windows, Mac, and Android for $49.99. Coupon code "SAVENS5D2" cuts the price to $29.99. With free shipping, that's the lowest total price we could find by $5 for either a physical or downloadable copy. It defends against viruses, spyware, and malware.
Of note, you can download a copy for the same price after coupon here.