Good deal for 3 different versions of Bitdefender, $19.99 is as low as you can get except for those 3 or 6 month free trials.
Tips: If you're using Internet Security, just buy the Total Security and contact their customer support. Ask to "downgrade" to Internet Security and they will give you a new license key with 60 days extra.
Make sure to untick auto-renewal for this order if you don't want to be charged every year (thanks pennypincher98)
When's the last time they did a 3 or 6 month trial? Haven't seen any lately.