I don't think you will find a lot of variation. If you look very closely at the bottles you will see that the descriptions are often careful to be precise but are ultimately misleading -- they look like they are made in Italy, or France, and are usually completely synthetic and often synthesized in New Jersey but have very Italian looking bottles. Notice that the discussion above about the Code of Federal Regulations seems to miss the point that the labels DO NOT say "natural truffle flavoring" but avoid the word natural because they are artificial. (Also many small production flavorings are not always in compliance with labeling laws). If you're familiar with truffles, white or black (Perigord or Burgundy/summer/winter), your first experience with truffle oil is likely to be amazement that there could be so much truffle flavor for so little money. However, as with many synthetic products (vanillin, for example), after you've used it a few times you may begin to have a sense that you are dealing with a one-dimensional flavor that is not really comparable to the real thing. In short, most if not all "truffle oil" - even from reputable truffle merchants - contains no truffle. The points above about the ubiquity of truffle oil crowding out appreciation for the real thing are well taken -- look what has happened to Balsamic vinegar, where people who call it "Balsamic" may scorn or waste the real thing if they encounter it.