I bought some from Germany when the pound was strong against the Euro, but no idea how much 3-in-1 costs so can't compare. I think it is just a highly refined mineral oil, claimed to be non-carcinogenic.
Used as a 3-in-1 substitute, I find it works just fine.
Used as a rust inhibitor/bedway lube, it works quite well, but does not last forever when handled, and is not quite as effective a lubricant as a paste wax. When turning wet wood, I find that neither wax nor Ballistol protect the lathe bedways for long so tend to use Ballistol due to ease of application.
It is very clean and does not leave an oily residue, it's very quick and easy to put a quick wipe on bedways and tools without worrying about mess.
It can be used on leather, wood - and dogs paws!
The smell is indescribable - although Wikipedia says: "a sweet and mildly pungent smell similar to black licorice"
Duncan