and this is why it would fail
the reason people charge extra selling vintage, or even non vintage stuff locally is because they need to import it in the first place.
the only way to set up a shop dealing in new items, would be to set up a line of supply with hasbro, or make your prices high enough to cover both your costs and your profit margin, noone is going to lose money just to sell collectors some cheaper toys, and if they do they are both stupid, and on a downward spiral to poorness.
As for selling vintage stuff, you would have to find a decent source of parts and bots to sell, something that is harder to come by here in aus when compared to the UK or USA, who have a much larger population base. It would require a lot of work just to build up a small stock of G1 parts, and even then, the prices would be higher than most likely what you could pick them up of a US site or ebay, because the more hands it passes through, the higher the price is pushed per part, because in the end its a bussiness and everyone wants to make a profit.
Some online stores prices are ludicris, and that could be because they were retarded and imported from a more expensive source than what some of us have in the past.