Question: I recently learned about using ScoutPal for book scouting, but I'm not sure whether I need a barcode scanner plugged into my phone to input the ISBNs. My initial take is that a scanner is unnecessary, just because there are many books without barcodes. So which is better: using a scanner, or just keying in the ISBNs?

Answer: You're right, a lot of valuable books (especially older out-of-print scarce books) don't have a barcode, and some don't even have an ISBN. So to check these, you'll need to type in the title and author name.

For other products like CDs and DVDs, you can scan or type in the UPC code to get the price on Amazon Marketplace.

I've always used a T-Mobile Sidekick phone that doesn't support a scanner, although I understand the newer Sidekicks have a working USB port. It's not a big deal for me to key in the ISBNs with my thumbs (although if you had really big thumbs it would be a problem). I have seen guys at book sales using scanners, so that they could go through whole stacks of books in a few minutes.

To tell you the truth, checking book prices via cellphone takes some of the fun out of book hunting. If you deal with books long enough you can start recognizing a book that is worth money just by looking at it -- or at least you can recognize those books that are likely to be valuable. When books are cheap enough, say $1 or $2 apiece, I don't even bother looking up the prices.

But this trial-and-error method works well only if you have a big selection of books to choose from at low prices. If you're shopping in a used bookstore you'd definitely need to look up prices on Amazon Marketplace.

The most popular cellphone-lookup services are Scoutpal, BookHero, AsellerTool, BookScout, and BookDabbler. The fee, about $7 to $10 a month, is well worth it if you go to lots of library sales. These services will bring up your price quickly, without having to scroll around on Web pages.

Most of these services have package deals where you can purchase a phone with a compatible scanner.

See a real-time list of the most highly sought after used and collectible books.

Read more free articles on selling used books profitably online: http://www.weberbooks.com/selling/selling.htm

Steve Weber is author of "The Home-Based Bookstore: Start Your Own Business Selling Used Books on Amazon, eBay or Your Own Web Site" (ISBN 0977240606). Got a question for Steve? Send to: steve_weber@yahoo.com