Our ds uses piedro boots (as well as AFOs sometimes) and they were always wearing out when he crawled about. A big hole would appear at the toes.
So...my dh painted a layer of Araldite glue around the toes (of the boots, not my ds feet!) and they have lasted ages looking new. Once the glue has worn a bit he has painted another layer.
Now my ds is in AFOs we bought cheap trainers, and my dh has just painted those as well. The glue sets to be almost clear in colour, and shiny. But I don't really care what they look like tbh.
Hope it helps!