The comfort of the shoe depends not just on the materials used, but on the style, 4 inch stilettos are not designed to be comfortable, if they feel comfortable it is a bonus, that is not the first criteria.
Nothing solves a bunion problem except an operation to remove it.
What you do get with designer shoes is more attention to the inner of the shoe, budget brands have to mass produce and put all the effort into the visual impact of the shoe. the more expensive brands use better quality linings and soles to give the shoe value.
i always say buy the best you can afford in the sales and you will get a good quality bargain.