not sure are you talking about buying products or only buying bitcoin. for buying products with bitcoin is an good idea , if some shops allows bitcoin to buy product directly from wallet or bitcoin debit card is good thing for the bitcoin industry . i seen on this forum some threads mentions about bitcoin debit card and buying products on shop 
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He is talking about bitcoin buy and sell with fiat currency.Like in London have a shop where you can buy or sell bitcoin with pounds similarly as in Shanghai you can buy or sell bitcoin with Yuan.I would be great if every big cities have a shop like this.people will be most encourage to use bitcoin..Do these shops provide any other services? Buying/selling BTC only doesn't sound like a robust business model.
It would be perfect if all the 'money shops' (where you can exchange currency, cash cheques, sometimes buy/sell gold etc) started trading BTC. Seems like a natural choice. Could work well especially at the airports where there's potentially a lot of people with some foreign currency cash left-overs which they could use to buy small amounts of bitcoins out of curiosity.