I always shop online to buy things like office supplies because I know I will always save money. I also look for product information online. For example, I checked into a toner blog when I needed to buy toner. I know some people are not real comfortable shopping for things online but it is sites like that that more than make the experience worthwhile.
If you shop in a store, there is a clerk or assistant there who can answer questions for you. If you tell them what machine you are working with they can put you together with the right toner. They can tell you if there is a generic equivalent that will match your printer. They can give advice on troubleshooting and so forth. Customer service representatives do not know everything but they can usually answer basic questions and point you in the right direction.
This is the only way in which shopping in a store is better than shopping online. After all, online is cheaper and gives you access to more options. But if you cannot ask anyone about what you need, then it does not matter how cheap it is. This is where a toner blog or other info site comes in.
Blogs cover all sorts of topics. They update frequently in response to the latest developments and they link directly to the sources of their information. In this way they are superior to a store employee. A little reading and you will be all set.