We buy based on our perception of the value of an item to us.
Even individuals with a very limited disposable income will find a way to buy an item that they really want. If you asked them why they chose a more expensive brand over a cheaper one, they would be able to give you a number of reasons. It could be the style of the item or feedback from a friend that suggests that a particular product will last longer. Safety could be an important factor. It could be that the product is a healthier alternative.
It’s also still the rule, rather than the exception, that price and quality go hand in hand. So unless there’s been a technological revolution that’s restructured the pricing parameters of the market, a cheaper brand will usually be perceived as being of a poorer quality.