Picking for books is actually called “book scouting” Professional book scouters have wonderful tools to help them find good titles for resale. Many have PDA devices with millions of ISBN numbers and prices loaded in them. They will also have a barcode scanner to quickly read the barcode, and search the database immediately, giving them a yes “buy”, or no “skip” tone. Todays smartphones have barcode reader software in their cameras, giving you a similar tool, and taking you to Amazon, etc. This venue is also called book sweeping. Sometimes at library sales you’ll see dozens of these book sweeps with boxes and cases and carts of books. They have active online bookstores on Amazon and other book selling sites.
While we are on books… READ! Knowledge is power! Find books on your primary inerests. Gather prices. Get catalogs and study them. Find something when you are out picking, but don’t know much about it? Write the type or model number down, do a search, find it’s value, etc. Next time you see one, you’ll know if it is a good find or not, and be able to add to your expertise!