How I Turned $1,000 Into a Million in Real Estate - In My Spare Time. Isn't that a great title? I love this book. I've never actually read it, although I've leafed through it to see why it's so popular. The first line is ''The road to riches is paved with borrowed money.''

I've owned dozens of copies of the book and its two subsequent editions, How I Turned $1,000 into Three Million in Real Estate in My Spare Time and How I Turned $1,000 into Five Million in Real Estate in My Spare Time . The book is out of print now, first published in 1959 and last published over twenty years ago. But until recently, people paid big money for the book, because it's full of practical advice on how to buy houses, fix them up, and rent them out, at a profit.

So while I have no aptitude or desire to make money in real estate, I've made some money (not a million) selling How I Turned $1,000 into a Million, et al. It's unusual in that it's popular and out of print, but not rare. Millions of copies were printed and many are still available. It was typical for us to buy a copy from a thrift store or library sale for a dollar or two (we found one copy for a quarter, and another for a dime) and sell it on eBay for $100. For a short time, the Five Million edition was selling for $140.

You may not be surprised to learn that the book is no longer in great demand, and while there are many copies listed for $80 or $100, a quick check on eBay reveals that the most recent sales were for $29.95, $10.50, and $8.75. A few copies are available on Half.com for 75¢.

The downturn in the real estate market is certainly to blame, at least in part. Fewer people think this is a good time to get into real estate for fun and profit.

It's hardly a tragedy – there are plenty of other books that can be found cheap and sold for a nice profit. But the market doesn't stand still. Another book that was in demand a few years ago was Wall Street: The Other Las Vegas by Nicolas Darvas. It's a sure-fire method to get rich in the stock market. It was long out of print and selling for between $50 and $100 online when I first learned of it. When a small publisher released the book in a new format for $14, I bought a few dozen copies, hoping that if I sold these quickly, I would make a small profit.

I did sell most of them at a profit, but at decreasing prices as the books became readily available. Then the publisher stopped printing the book. If only I had bought more and not sold them right away! The price rose steadily to its old level. But now the book is once again in print, by a different publisher, and you can buy copies new for $14 and used for $6.

Now what? Should I scoop up copies of How I Turned $1,000 into a Million, anticipating an eventual return of the real estate market? Should I stockpile Wall Street: The Other Las Vegas for when it goes out of print again? Or has the demand for these books dried up for good? My bet is that the time for these books has passed and it's time to look for different book buying opportunities.