I'm pretty sure I'm not pretentious in any of the ways that other people are listing. I have preferences for a few higher-cost things, but it isn't in an effort to seem better than others, it's because I think some things are worth paying a bit extra for.
Oh, I thought of something. I feel irrationally proud when I buy an "intelligent" nonfiction book like my ones on string theory and evolutionary genetics. It makes me feel smart. Though I would never buy or read a book for that reason, of course. Does that count as pretentious?