Bad Buyer
Q. Can I get advice from a full-service store and then use my new knowledge to buy at a discount retailer?
A. Many years ago specialty items (this once included high quality cameras and stereos, though these are rapidly becoming commodities) were only sold in high-end stores, which provided both advice and merchandise. Already in the 1970's these items began to be readily available in large discount stores with little sales support, and today virtually everything is available via the internet. This puts a squeeze on the specialty stores; they can compete with the internet if their disadvantage in price is offset by their advantage in expertise.
But sometimes customers want the best of both worlds; in such an environment, knowledgeable sales support cannot thrive.
One approach that has often been taken to this problem is ona'at devarim – oppressive or exploitative speech. The mishna states, "Just as there is fraud in commerce, so there is fraud in speech. You shouldn't say to [a merchant], 'How much is that item?' if you don't intend to buy." (1) At the most basic level this prohibits taunting or tormenting the seller, but it would also include pestering him with questions for your own benefit if you have no intention of buying from him.
You are taking the expertise but not paying for it.
However, there is an additional problem here. You are not merely wasting the seller's time, you are actual taking advantage of a service he provides but violating the conditions under which he provides it. An upscale store doesn't sell merely merchandise; they sell a combination of expertise and merchandise, which is naturally more expensive. But what you are doing is taking the expertise but not paying for it.
This is not unlike trying a free sample of an item when you are unable to buy it. (If you are just convinced you won't like it you can still try it. After all, that's why they offer free samples, to convince people who are sure they're not interested.) An interesting Talmudic passage discusses this exact problem:
All subterfuges are forbidden except for the following which is permitted: Someone who has [let blood] and has no other way [of getting wine] . . . can go to a [series of] wine shops [and taste a samples], until he has drunk a full cup. (2)
This is a subterfuge because the wine shops allow you to taste so that you can make sure you like the wine before you pay for it – not to give you a free mouthful. It's permissible in this unusual case because drinking something substantial after bloodletting is critical for health; not doing so could be dangerous. We have a combination of three elements: the need is compelling, the cost is minimal (he takes only a sip of wine from each store), and there is no actual deceit. When you taste a sip of wine you are not obligated to buy a glass even if you like it. The problem here is bad faith – you have no intention or even ability to buy the wine.
Your case is a similar subterfuge (the seller's time is probably worth much more than a sip of wine), but it lacks the key condition that makes it permissible. There is no compelling need to get a discount on electronics or sporting goods.
If you want to buy merchandise from an online or discount seller, you should solicit advice from friends, books, internet sites and so on, but not from full-service merchants. If you go to a full-service store in good faith and decide you can't afford the merchandise, you don't have to buy there – there is no contract and even the store itself wouldn't want to make you feel obligated because it would deter customers. But you must have a good faith intention to compare the value you obtain there with the value you can obtain from some other merchant.
SOURCES: (1) Mishna Bava Metzia 4:10. (2) Babylonian Talmud Shabbat 129a