You spent over $800 on lights for 2 bikes? Huhhhh???
I do almost all my riding at night and I got 2 cygolite Metros for just over $100 and a hot shot 2 for $25. I have 4 bikes and I can switch all 3 lights from bike to bike in about 2 minutes.
I don't think commuting costs is the problem I think your just scared of the dark..
[h=1][/h]