Preservation of cultures?

[Bertil Lindstrom]

Hi out there!

How do I preserve the cultures for future use?
I have read about deepfreezing in liquid nitrogen, but that is out of
the question -:)

Somewhere else (Stamets ?) talks about storing cultures in "mineral
oil". 

Now what excatly is "mineral oil"? Ordinary motor oil or cooking oil
or some special oil?

Is there any other cheep ways of storing live cultures?

/Bertil