I've been into literally all of these at one point or another. Miniatures don't come close. Cars are the most expensive, it's not even close. Second is a tie between guitar and guns. Both can vary wildly depending on your tastes. I spent more on guns, but only because I never got into "classic" guitars. I own multiple $1000-$2000 guns, I don't think I've spent $2k on my entire mini collection (2 years in). That said, at least if you are buying a gun or guitar people understand that it has value. People look at minis as toys or chunks of plastic. So spending $300 on minis seems like a big deal. A $300 guitar or gun is a cheap guitar or gun.