Leaning CTEK myself...those lights are purdie. I believe we have an AGM battery, correct? $60 looks to be the "best" price I've seen for the 3300, but haven't looked up on DD yet. Never thought of doing this, but the car does sit quite a bit in the winter...and probably even more so now that I lost my commuting partner.
2011 335i M-Sport, BMW Performance Powerkit Version 1, 35% F1 Pinnacle Tint