There is competition in the used book game because it is actually possible to make a living doing what I do. I see my adversaries packing their hauls into decent cars, sometimes with the help of family members. A good load of books found all of a sudden might be resalable for many hundreds of dollars. With diligence, someone working alone can make $1,000 per week; with a more insane commitment, or with the help of a wife or child, the business might yield more, especially once a sizable inventory has been built up.The author of those words works up to 80 hours per week scanning books, but a thousand dollars per week ($52 K / year) is a pretty decent business considering the amount of training someone would need to get into such a job.
On the job, he has picked up some interesting insights. Indeed the whole article is worth a read. Here is my favorite quote:
To increase your odds, it's important to maintain a territory. There are certain stores I go to almost every day. This behavior starts a positive feedback loop: If other buyers find little to their liking, they'll show up less frequently, and I'll get even more.