If it has no prices then I stick with the shops I know like Omni, Grump Store and hopefully soon the Gemporium I have no interest in wandering the universe for an hour to find the lowest price. I will just assume between the 3 stores I can find the item and buy from whoever has the lowest price. Everything in the game (except maybe some of the forged items) is a commodity. There is no difference in a refined block or a machine from store a or store b. Commodities are driven by lowest price.
Amazon also offers home delivery. People like the convenience of being able to have things delivered to their door. Amazon does not always have the lowest price, but I will buy certain things from them in order to save having to go get it. So far, that is not possible in boundless. A shop close might be more attractive, but if I do not know what they have and how they price, I will go not be going there.
Also the volume game, can the larger stores not already be doing that? if they buy all the resources and only make a 2% profit why not? This is a game it is not like they have to meet payroll or will have to close down the shop if they do not make enough profit. As long as someone generates a surplus of coin they can stay in business.