Graeme is right about phantom power supplies, (although his link brings up the Google home page for me...) Search for auxilliary phantom power supplies. Naiant used to have several...
There were some condensor microphones that were battery powered and didn't need phantom power. The Equitech CAD-200 from Conneaut Audio Devices comes readily to mind. These things had two high current draw 9V nickel hydride batteries inside, and would give you about 5 hours of recording time without need for phantom power. However it was a real PITA to unscrew the body housing, partially disassemble the mic, take out the batteries and replace, if you wanted a longer run time. (There was an integral charging circuit in the mic which would recharge the batteries if you plugged into phantom power, but it took a long time...)
http://www.soundonsound.com/sos/1997_articles/jun97/cadequitek.html
The bit about unscrewing the microphone housing is not to be taken lightly... I once bought one of these for a song from a "junk bin" sale at the music store because the threads were stripped (probably from too many unscrewings and re-screwings without care...) and repaired it by drilling and tapping for a slightly larger screw in the body. I don't think these have been made in years, though, and they are not what I'd recommend for music production. An excellent mic for voice-over work or perhaps for broadcast work, but the "shock-mount" is not a shock-mount at all and works very poorly!