Regardless of whether you shop online or you shop at a store, it always make sense to look around and get the best value you can. When doing that, you have to weigh the different values behind it. For example, you are looking to buy yourself a nice jacket. Online you will always find it cheaper but the downside to it is twofold. Firstly, you don’t know if the thing is genuine or not. Secondly, you don’t know if it will fit you.
Of course this rule only applies to standard every day items, you are not going to go out and buy plants or paving from an online store! Can you imagine the shipping costs alone?? If you are interested in gardening and paving, it should be purchased from a professional local store.
In a store you can feel the material, try it on and if you have a problem with it, a quick trip back and you can return it. That luxury of course costs you more. Its a trade off that is up to you to decide if its worth it.
Some common rules can be made from it though. If you are shopping online, always buy from a reputable seller, ensure the product is by a reputable brand and make sure its not something that is size dependent. A cream or some beauty products is fine online, however, buying a jacket is a tad more risky, regardless of the brand!
Personally, any form of clothing or shoes that I purchase is always bought from a store or if you are looking for a bargain, you buy second hand from a thrift store or from other sellers advertising listings.