Can i buy a pair of Guinea Pigs without actually seeing them ? Pls check the additional details :)?

I am thinking of getting a pair but these arent available in my city.A pet shop owner says that he can import them for me from another city and give them to me but this means i dont actually get to see my piggies before buying them.I am worried as to how can i blindly trust the guy that the pigs would be of good health and without any problems.He is a reputed dealer in pets and assures of the best pair but i am still concerned. Please advice.