NEW YORK When Amazon.com’s ground-breaking Kindle e-book reader came out in 2007, it cost $399. Now, some e-readers, including the most recent Kindle entry, can be had for just north of $100.At the price of five or so hardcover books, it’s close to impulse-buy territory for many people. And if you give in to your desires, what do you get? Our test of five e-readers priced from $114 to $164 finds that cheap, in most cases, means good value.All five have black-and-white screens that are about half the size of a paperback book. They can connect wirelessly to the internet for e-book downloads. I didn’t look closely at battery life, because with one exception, they all claim more than a month of use. The company time machine was occupied. Here’s the rundown:l Kindle with Special Offers ($114) is the cheapest Kindle model yet. It’s indistinguishable from a device that costs $25 more, except that it shows advertising as its screen saver and at the foot of the menu.You don’t, mercifully, see any advertising when you’re reading, and overall the ads didn’t feel intrusive. The selection was limited, for the most part, to Oil of Olay, Visa and a car company or two, making us wonder if advertising companies are really sold on Kindle ads.And it left us wondering if there is any attempt (or might be in the future) to profile users based on their Amazon account. That could get a bit embarrassing because the ads are visible if you leave the Kindle lying around. (“Oh, so you’re into romance novels? Who’d have thought?”) The Kindle doesn’t come off very well in this test, chiefly because the screen isn’t touch-sensitive, forcing you to navigate with the aid of buttons. It also devotes a lot of space to a keyboard you won’t use much. It’s also larger and heavier than its closest competitors.There’s another difference between the Kindle and other e-readers that few appreciate. The No. 1 sleeper issue with e-books is that the biggest e-book stores tie their books to their own software. For instance, Kindle books can only be read on the Kindle or Kindle software. If you want to trade your Kindle for a Nook in the future, you’ll be leaving all your Kindle books behind.The solution is to not buy books from the big stores and to not use a Kindle. All the other e-readers I tried will accept books from Google Books and smaller online stores. These books can be read on smartphones, PCs and tablets as well.Buying books this way is more of a hassle you’ll have to download them to a computer, then transfer through a cable but it’s more likely you’ll be able to read your books on the device of your choice in the future. I also looked at the Kindle with Special Offers 3G, which costs $50 more. It can download books through AT&T’s cellular network. This is a feature none of the other devices in the test have. If you’re giving an e-reader to someone who doesn’t have Internet access, this is the one to get.l The Barnes & Noble Nook ($139) is another small triumph from a bookseller whose first e-reader, the original Nook, was shockingly bad. Less than a year later, it redeemed itself with the release of the Nook Color. I still consider that the best dedicated e-reading device, but its $249 price tag places it out of the entry-level category.The new monochrome Nook has a touch-sensitive screen, making for an easy, intuitive interface. It’s also small and light. In short, it’s a pleasure to use. Like the Kindle, the Nook uses a screen with “electronic ink” technology. It makes for long battery life and very good legibility in bright light, where colour screens look dim.But it also comes with big drawbacks. It can’t show color and can’t be backlit for legibility in low light, and it takes time to switch between pages. The slow screen can also make the e-reader annoying to control, but the Nook makes the best of it by making the screen touch-sensitive. The Nook also suppresses the “black flash” phenomenon seen on the Kindle. Whenever you turn a page on the Kindle, the screen first goes black. This is how the e-ink resets itself so it can show the new page cleanly, and some people find it jarring. The Nook only flashes this way every sixth page.l Kobo eReader Touch Edition ($130) is quite similar to the Nook, but takes the touch interface one step further by eliminating page-turn buttons. That leaves only two buttons, for the home screen and for power. Style-wise, this makes it the iPhone of e-readers. It, too, is a pleasant experience, and it suppresses the “black flash” in the same way the Nook does. However, I found it slightly inferior to the Nook in that a page often shows a ghost image of the previous page. It looks like someone wrote the last page in pencil and used a bad eraser on it before putting up the new page. The Kobo eReader also provides fewer options for text presentation. For instance, it won’t let you adjust margins or line spacing.l Aluratek Libre Air ($130) is an odd duck in that it isn’t sold by a major bookstore (Kobo is affiliated with Borders) and it doesn’t use an e-ink screen. Instead, it has a reflective LCD screen, somewhat smaller, darker and greener than e-ink but more nimble and without ghosting problems. When I reviewed the Libre Pro a year and a half ago, I preferred its LCD screen over the e-ink readers available at the time. But e-ink screens have improved and the LCD has not, so my preference has shifted. The screen is still passable, though. It uses more power than e-ink, so the Libre Air is only rated for two weeks of use. The really big problem with the Libre Air is that it has a horrible bookstore interface. It’s supposed to be able to download books from the Kobo store through Wi-Fi, but this was so difficult that I just gave up. You can load books on the Libre Air through a USB cable, but then you might as well get the Wi-Fi-less Libre Pro, which costs $90. I name the Nook and the Kobo eReader the winners of this test. I still think the iPad is better as an all-around e-reader because of its colour screen, its backlighting and its size, which makes it ideal for PDF files. But the iPad starts at $499. At $130 or so, I can’t fault anyone for getting a dedicated e-reader instead.