heya richard
Most folks have 240 in their homes...the dryer outlet is probably the most widely available 240 source out there. Quite a few BIG grows use 240v ballasts, FWIW.
There are "smart" ballasts out there that can detect the v coming in and switch to adjust...and at some point these tings will be plug and play all around...detecting the waatage of the lamp/power/and hps or mh and firing whatever light is screwed in the socket with the proper juice.
the future looks bright.....
ww