If this solution (?) is not presently patented/marketed, and hasn’t been proven infeasible, remember where you heard it first – and keep it a secret.
The soles of most cheap shoes wear out long before the shoes’ upper parts do. Of course, getting new soles put on such shoes is more expensive than buying another pair of cheap shoes. Why can’t I buy cheap shoes that fasten their soles to their uppers by means of zippers? A new sole made to fit a given size and type, or more than one type of a given size, of cheap shoe, which sole includes half of a somewhat rugged plastic zipper, should not cost more than maybe half what such a new shoe would cost – you think?
Ray (I’ll take it for $zip.)