Why exactly do you think this would happen? It doesn't actually make sense. Let's say Company A charges 2$ for an apple and each apple costs 1$ to procure, and then at some point a UBI is implemented. What changed that suddenly allows company A to raise the price of an apple without being undercut by Company B? The cost to procure an apple might increase somewhat because laborers have more leverage under a UBI, but there's an upper limit to this with automation anyway. A more equal distribution of wealth in itself will not cause any increase in the cost of goods.