The bowler hats worn by cholita women are not decorations but genuine cultural markers, and buying one is one of the better souvenirs from La Paz. The main hat shops are clustered along Calle Sagarnaga and the Witches' Market area. The hats come in different sizes, colours, and qualities — the better ones are made of felt and hold their shape; cheaper versions are lighter and crush more easily.
Specialist hat shops have fitters who will adjust the hat to your head on the spot. Don't buy a hat that doesn't fit: the whole point is the tilt, and you can only get the tilt right if the hat sits properly. Prices range from around 50 to 200 bolivianos depending on quality and how aggressively you negotiate. Buying from an established shop rather than a street stall means you're more likely to get the real thing.