This was a constant problem at Borders when I worked there: the vast price difference between books being sold online through Amazon (Borders' partner at the time) and the prices on the shelf.
We were instructed to tell customers who were curious about why the books online were 50% cheaper at times that the online store and the real world brick and mortar store were separate businesses and the real store had, y'know, overhead
invested in employees and stores and chairs and 50,000 in-store books to browse.
Which is all true, but it's not persuasive
A bookstore that does not want to sell you books
As I stood in line, I looked inside the dust jacket to check the price. There were no discount stickers attached to the front cover, unlike the bestsellers and other new arrivals on the display next to me that were reduced by 20% to 30%. The full price of the book seemed to be (a lot) more than the price I remembered from their website that morning. I opened Safari on my phone which connected quickly thanks to the instore "complimentary Wi-Fi". Yep, the price on their website was quite a lot less.
I was called forward to the check out register by a friendly representative.
"Excuse me, what's the price of this book?"
"Well that one's full price", he looked inside the cover, "so that's $29.95."
"And with a membership, is that reduced?"
"Yes, as a member you'll get 10% off."
"Do members also get free-shipping from your online store?"
"Yes, they get free shipping."
"And if the online price is 10 bucks less", holding up my phone at the appropriate page. "Am I better off just ordering it online?"
At this point the representative, by now clutching the book, began to recite a learned response that I later discovered was similar to these words on the barnesandnoble.com website.
"Barnes & Noble.com usually is able to fill your order with less expense than our retail stores, and we pass those savings on to our online customers. This is why our prices online sometimes are lower than prices in your local Barnes & Noble store."
The still friendly, but now somewhat dejected clerk added, "Yes, you can order it when you get home, and you'll save some money."
"Or I can order it now, on this", gesturing with my phone. "Thanks."