I felt somewhat bad about just handing the Cashier the book and leaving the store, but it was a really long line.
It's brilliant. Though I usually try to buy some things in the shop too, if it's a place I want to survive.
* (just show it to them if you have a smart phone).
And as long as you aren't damaging the books, and as long as the store isn't so crowded that you're discouraging other potential customers, the store looses absolutely nothing by having you there. In fact, they always gain something - there's always the off chance you'll see something and decide you don't want to wait for it to ship.
Borders is a retail store heavy company, and they haven't made any significant changes in their store in response to competition from online stores. That's a huge red-flag and is nobody's fault but theirs.