I don't worry much about what my shoes are made from or the price but also I do not buy many. I think I own four pairs of shoes, one that I wear to things like weddings and funerals, two for hot summer weather, sneakers and winter boots, and I do not remember when the last time i bought a new pair was.
Really I think the whole point to being more 'sustainable' is not about the little details of what the thing you buy is made from but that you do not buy the ones you don't need.
Some people buy hundreds of pairs of shoes. It does not matter what they are made from that is for sure a bigger eco footprint than someone who has less than 10 pairs.