I prefer to buy in the online store which has a fast worldwide shipping, good security, have a lot of products, I can have my own page to check my order and my balance, 24/7 online chat that can solve the problem if any. The online store should have promotions or discounts for their customer so that they can attract more customers to come and buy the product. Maybe Amazon or eBay can be a good example for you to build your online store.