Considering the alternatives are metal and glass, I'd assume that the cost difference would be exponential, especially if the most common alternative is banned and transport will be much heavier.
Human ingenuity knows no bounds and it will be a market opportunity for new entrants and innovators.
- are the overall costs of plastics (namely pollution and its environmental and health effects) higher than the costs of banning plastics? Seems like a clear yes.
- what are the redistributive effects? Seems like: consumers are net winners (lower health effects, some or all financial costs of switching away from plastics are passed down to consumers through higher prices); some firms are losers (mainly those who produced plastics or used a lot of them) and some are winners (newcomers, producers of no plastics solutions, transporters).