If you feel you want to purchase something from the internet, go ahead and click "add to cart". Do not go to a place of business offering the same products and tell the people working there that you are only there to check their pricing against the internet. That's very disrespectful to the employees and does a disservice to you because the employees don't feel like going the extra mile for you. They figure they've lost another sale to the internet and their enthusiasm ceases.
I realize why people do this. As an employee of a wholesaler, I see it every day. You can buy faucets, tubs, toilets and just about anything else you could want via internet. The prices are cheaper because the person offering the products is just going to pick a box off the shelf and send it to you, along with outrageous processing and handling fees. The customer figures that in "this economy" he should be able to drive down the price of the item he is looking at purchasing by telling the business he's shopping at what the internet is selling it for. Perhaps this works sometimes, but it won't get you far at a wholesaler. Why? Because they are already offering it to you as cheaply as possible.
If you must patronize the internet and compare pricing, please keep that detail to yourself. It is so deflating to work with someone and try to give them optimal service and then get told you are competing against the internet. Internet sales are so cheap because they don't have to employ people to help you decide which product is best for you and show you how it works and what your options are. Some people seem to want the best of both worlds by shopping the internet, then going to stores with employees to get that expertise and wind up wasting their time. That's time they could have spent with someone else who does want to purchase the product.
Either buy from the internet and boost that company's sales and economic outlook, or buy from a store with employees. But kindly stick to one or the other. Wasting a company's time when you don't intend to purchase the product there is counterproductive to the economy.