Whoever told your friend that the single lamp magnetic ballast isn't produced any more is full of beans.
Many electronic(T8) ballasts can be used with a capped lead to run a lesser number of lamps than their main rating, and are marked as such.
I've seen lots of wild combinations of mismatched ballasts and lamps. Bottom line is they don't last any time if they light at all, which they very often won't.
Read the labels, and follow them!
