Looks like the Amazon price is $16.79, and this customer chose to pay the full MSRP of $27.95 to buy from another store.
To me it's the same. You're supporting the people for whom you have some affinity by nationality, ethnicity, history, interaction, geography, etc. However, most people (with few exceptions) don't show the same favor for goods one could argue would benefit the local industry and our society (and also be contrarian to globalization) by buying the more expensively produced local or at least American [or native nation(ality) of shopper] goods?
I'm not advocating for either, you do as you choose, but it seems a bit contradictory or maybe people identify more with the bookseller (who is just a middle person) rather then the cobbler or shoemaker, tailor or seamster/seamstress who actually physically make the things themselves.
* They don't trust working conditions abroad; Amazon is 'local'-ish labour too. I'm sure I've read online that their working conditions aren't amazing, but it's not a Bangladeshi garment sweat shop who are paying bribes to the local mafia...
* They worry about the transportation costs on the environment. There's no particular reason to think that your local bookshop would be any better at reducing environmental impact than Amazon
* Means of production and providence are important to people in food products and products made from natural materials - those don't really apply to fungible books that have come from the same producer
* Keeping money locally in the community, with the idea that there will be some kind of trickle-down effect, or collateral benefit (like bookshops having reading events for kids) -- this seems to be the only really applicable part here, and I guess each consumer needs to ask if that's worth the extra cash for them
A shoemaker moreover would have more involvement [manufacture] than a mere "merchant" which is what booksellers are.
There's a romantic aspect to being in bookstores that just isn't found with stores of other types of merchandise.
People don't flock to knife stores for knife signings. They don't sit down with a cup of coffee inside the knife store with other knife enthusiasts and talk about the latest knife they sharpened. They don't take one knife off the shelf, sit in an overstuffed chair and flip it a few times then put it back and take down another, all with no expectation of purchase or pressure. etc. etc.
With regard to knives, there are some people who do sit down and discuss process and knifemaker and tradition, history of a particular blade, provenance, etc. So it does happen. Chefs tend to have favorites. Swordspeople tend to have favorites.
But I have to admit, I think your point about perceived "intellectualism" might have merit (and explains the book part, but not the bookstore part but perhaps it's social aspect of the bookstore as you imply.
Message board theorizing aside, the best way to support independent businesses is to do business with them.
If your business is actually a charity, consider going non-profit. Non-profit places to get books already exist though, they're called libraries. Independent bookstores sell the same books for more than Amazon so they can't compete as a business and they cannot compete with the state sponsored information access the local library system provides.
All that's left is to open up an overpriced coffee bar and serve the hipsters who find the irony of the bookstore's continued existence appealing enough to walk in the door. It's already amazing such stores survived Barnes & Nobles rise during the 90's and early 00's.
Where?
http://variety.com/2015/film/news/movie-ticket-prices-record-high-2015-summer-blockbusters-1201545600/