I will personally not buy a pair of shoes until I wear and see how it feels and looks on my feet. You haven't mentioned the website URL, so difficult to say if it is reliable.
First, check if there is positive user feedback on the website (like amazon.com, ebay). Second, check to see if the vendor is legal and not selling counterfeit products.
On the internet, it's all about trust. If you trust the website then go for it, otherwise I advice you to pay a little bit more and buy from a proper shop.