Which kind of clothes/cars/books/hobbies/etc. do well-off people buy and do? They don't have to be filthy rich, but they just have to be wealthier than most middle class plebs.
There's a whole book about your exact topic called The Millionaire Next Door
tl;dr they buy nice used cars, shop at kohls, and do things that give them pleasure and don't give a fuck about what is "in" or "looking rich". It's the people making $50k who really try hard to look rich and fuck up.