to ozonate olive oil properly you need a high grade unit. you need to ozonate the oil for up to two weeks. several people on the oxygen forum have posted about burning out their cheaper units by trying to ozonate olive oil with them. the motors just fry. also you need to put it somewhere outside of your house so you don't breath the ozone gas all day. so its not a small thing.
but you can get an inexpensive one for doing water now for around $50! just three or four years ago the cheapest on the market was $275 and up. the chinese have perfected making these cheap ones and you know why? because their water is so fouled up by pollutants of every known variety they basically have to ozonate their water just to keep from getting deathly ill.