I wonder if that sale is over because when I tried to buy it (logged out) it showed $39.99 and I couldn't get it to show the $19.99 no matter what I tried. So I logged in because I do get a discount on accessories, so I picked it up for $29.99 It's in my stocking right now, just waiting on Christmas.
But yeah, like someone else said AOSP roms help battery life so much.
I am running Liquid Smooth 3.2 and with 2 email accounts refreshing every 5 minutes, and 1 push exchange account, and a facebook widget updating every 5 minutes, and the beautiful widgets weather widget updating every 15 minutes, I still get decent battery life out of my stock battery.
But I am on WiFi about 70% of the day normally, so I think that helps a lot.
But I can't wait to start using my new Rezound battery.