I'm using an "ecological extra virgin olive oil" from ICA, a Swedish supermarket chain. It is "their own brand" so to speak, produced in Italy for them and supposedly without the use of pesticides and so on. Price is around $22 per liter which is normal for a decent olive oil. It has a very mild and fresh taste and light color, I don't think it is very difficult to find something similar where you live.
The salt: ordinary coarse Sea Salt , an inexpensive generic brand. I grind the salt to a fine powder in an ordinary salt mill right before use.
I have no idea about the significance of the particular salt and oil types. Quite frankly this is what I found in the kitchen when I started to experiment with this treatment. You should observe that the classification "extra virgin olive oil" can be tricky, there has been quite a lot of cheating in the olive oil industry so you cannot be entirely sure what you get. The same goes for "ecological" so maybe it is better to choose the reputable brands? Anyway, the stuff I use works fine and is excellent also for salads etc... :)
Perhaps equally important: use a washing lotion that is gentle yet effective enough to remove the oil after an hour or so. Eucerin Ph 5 works fine for me. To prevent dryness and scaling after the treatment, I found Ceridal lipogel to be highly effective applied in a very thin layer over night. Perhaps some people would find it necessary to use a thin moisturizing cream also during daytime, Ceridal lipogel is probably too greasy for most people's taste here. I don't need that, though.