Flowing thru a Secondhand Bookstore

I have always walked past by this secondhand bookstore. Sometimes I would be going up SOHO for brunch, other times I would be coming back down to Central after dinner. I see book stacks all the way to the ceiling even through its windows. I decided to get off the escalator today, and take a look at the Flow Organic Bookstore.

This shop sells books at 45% to 60% of the list price but buys them in at 5% to 10%. So at 35% to 55% margin, what service does this store provide the world?

• These are secondhand books. Therefore by definition, you only get books that are "pre-screened", i.e. books at someone else found good enough to buy.
  
• You only get books that someone's willing to part with for 5% to 10% of what they paid for. (Hmm..)
  
• It's good for the environment. Every book recycled saves a new book from being bought and collectively, save at least a few trees. Books is a medium whose value does not depreciate greatly with the passage of time. You get the same knowledge and the same wisdom as long as the bindings hold together.
  
• It allows you to monetize your old books and free up capital for more books. Their disposal also cuts down your cost of storage.
  
• The lower cost of acquiring old books provides an easier mean for me to feed my book addiction.
  
• The lower acquisition cost also encourages me to try books that I wouldn't have otherwise read.
  
• I take a certain delight in discovering little gems in and amongst the stacks.
  

I wish there are more secondhand bookstores!