This question is acutely relevant today. You are shopping for something. Your plan is to go to a lot of brick-and-mortar stores, see the item, feel it, ask the salespersons lots of questions, then go home and order it on the Internet at a discount and save the tax. I know the halacha is that "you don't ask for the price of an item if you have no intention of buying". But here you are not just asking for the price. You might buy it in the store. The store should be aware of the competition (including on the Internet), can offer servicing in the price, etc. You just don't know. But the fact is that, most of the time, you end up buying it on the Internet. Is this ethical? If not, how is that different from plain shopping, with the Internet being just one of the venues for sellers?
From an article by Rabbi Meir Orlian, answering this question
It is permissible to browse, though, if there is a possibility that you might buy there. Any store owner knows that potential customers comparison shop and might decide not to buy there. (Pischei Choshen, Ona’ah 15 nt. 15) It is also permissible if you ask the store owner up front, “Do you mind if I browse the products without buying?”
Furthermore, browsing in a large store full of customers is permissible if you do not distract the salespeople, since the owner or salespeople do not note an individual person who enters and browses. Similarly, it is permissible to browse in stores that emphasize feature displays, such as FAO Schwarz, since the owner encourages people to view the display and does not necessarily expect a sale.
Finally, the prohibition of ona’as devarim applies only to a fellow Jewish storeowner. (Rama 228:1)
"It is permissible to browse, though, if there is a possibility that you might buy there. " How do you know you are not just rationalizing in your mind, knowing full well, from experience, that you'll most likely end up buying it on the Internet? (Buy a low-cost item from a store every once in a while, just to set your mind at ease?) Also, "browsing" is unlikely to cause scruples, but peppering a salesperson with questions would. Mar 25, 2018 at 17:43
2The test is to put yourself in the place of the shopkeeper. If you saw a person coming in to view in your shop in the way you describe, how would you feel about it? "What is hateful to you do not do unto your neighbor. This is the entire Torah, all the rest is commentary" (Shabbat 31a) Mar 25, 2018 at 18:51
@mau In a similar article here in the last paragraph, it said that it's basically up to you to decide if you're being honest, as this is really all in the mind. // I would also say that you can be certain that if a product is half price online, and ur just going in to check it out, that would be a case where you're definitely not going to buy in the store. Also if you have no money on you, that's also a reason not to go into the store when planning to buy it online.– aBochurMar 25, 2018 at 19:02
You already paid for the gas to get there, spent a good amount of time researching(and time=$), might as well keep people working and get home happy with the item in your hands, or as a present for the wife, etc. Getting a package a day or few days later is okay, but it's always better not having to worry about tracking, somebody stepping on it while it's on its way, etc. IMHO, of course.– GaryMar 25, 2018 at 19:06