QUESTION: I have lots of books I haven't been able to sell on Amazon or eBay. How many months do you let books sit on the shelves before you begin lowering prices?

ANSWER: I used to have very limited storage space, especially when I started selling books online. Back then I lived in a small apartment and had to rent storage lockers to hold my books. So after my first 18 months of selling used books I had about 10,000 unique books and was paying more than $1,000 a month in storage fees. I was making plenty of cash to cover the rental fees, but didn't want to commit to more storage bills. So I decided to delete all my listings for books where the price on Amazon Marketplace was under $4. Getting rid of those books was a pretty big hassle, so I've been more careful in selecting low-priced books since then.

But to get back to your question, deciding when to cut the price to remain competitive depends totally on the book, and how high the average price is online. For low-priced books that I want to sell as quickly as possible, I'll cut the price every week or so, just to try to get rid of the book before the price falls too far. But for higher-priced books -- say over $40 -- I am much more reluctant to cut the price. Maybe I'll cut it a penny or two if it will make the listing more visible. But if I think the other prices are abnormally low, I'll let the book sit there for six months or a year without even considering lowering the price.

I base this on two observations:

-- Buyers of low-priced books don't consider feedback much in their buying decision. So even though you might strive to have high feedback to be competitive against other sellers, buyers of low-priced books either aren't informed enough to consider a seller's feedback or just don't want to take the time to consider any factors other than price. So to sell a low-priced book you have to compete on price, just because most of the buyers for these items aren't going to scroll through to compare listings for feedback, condition, etc.

-- Over the long term, prices of low-priced books tend to fall, and those of high-priced books hold steady or go up. That's because low-priced books tend to become more available over time (more used copies appear for sale online and price-cutting ensues), but higher-priced books tend to be more scarce and as used copies are purchased, price tends to go up as they become more scarce. This is why out-of-print books are such a hugely profitable area for used booksellers. Also, the buyers of these books usually pay a lot more attention to the book description and seller feedback, so you don't have to compete just on price.

One more interesting observation I've seen in the past year: Last summer I moved to a house where I could store all my books in the basement instead of paying for off-site storage. I had to hire movers, everything got disorganized, and most of my books I had to delete until I could locate them again and organize them on shelves in my basement. I'm still re-listing them, and I've been surprised to find that many of my relatively low-priced books -- say those that were going for $5 or $10 on Marketplace last summer -- have doubled in value during those six months. Some of them, may a quarter of them, had become essentially worthless, worth less than a dollar or two, and I've been getting rid of them. But in most cases, whereas six months ago I'd have been beating my brains out to sell them at the lowest possible price -- now I'm selling them faster at double the price.