Ebook prices are all over the map, from free into hundreds of dollars. For independent publishers, however, Amazon has set the standard: for the highest return, books shall be priced at between $2.99 and $9.99. How do you price your ebook?
This is the second diary in a series; I suggest starting with the first one.
For the purposes of this discussion I'll limit myself to the Kindle. There are certainly plenty of other places to publish ebooks, but Amazon has the majority of the market. Additionally, this is for independent authors; the publishing houses have their own pricing strategies.
Selling on Amazon, you can price your book from 99 cents on up; however, to get the maximum royalty (70%) the price must be between $2.99 and $9.99. Thus, you'll make six times as much selling a book for $3 as you will selling it for $1. (The exception is picture-heavy books, as books taking the lower royalty rate aren't charged download fees, which really only make a different with large file sizes)
Due to this, the default pricing for most new nonfiction seems to be around $2.99, with novels ranging from $2.99 to $4.99; short stories still come in at 99 cents but then collections can be offered that cost more.
Of course, most independent nonfiction seems to be fairly short, which affects the price. My books so far are all for sale at $2.99, which is the most I felt I could get away with for the current length (my Amazon book used to sell for ten times that off Amazon, but there was less information available when I wrote it and I was selling it largely on the basis of my personal reputation rather than to the public at large). A longer book by an established author can certainly be priced at $9.99, but an unknown will have trouble getting people to take the risk at that price point
None of this is to say that there's complete agreement on pricing. Some people price everything at 99 cents, in order to get as many sales as possible. Some people try lots of different prices and settle on whichever one brings in the highest prices. Interestingly enough, because $2.99 has become the standard (much as 99 cents has become the standard for paid apps in Apple's app store) there isn't always a huge different in sales between those two prices. In some cases, raising the price can actually increase sales, because people associate a higher price with a higher quality product.
There's also the question of whether to offer an introductory price and then change it later on. If you raise the price, then people who bought early feel like they got a deal. On the other hand, the traditional publishers go with the high then low strategy: first comes the higher-price hardcover, for the people who want to read the book right away, to be eventually followed by a lower-price softcover and ebook for people who weren't willing to pay the higher hardcover price; this allows them to practice differential pricing in which people are charged the most they're willing to pay.
A higher price also allows more room for sales, such as the new countdown deals at Amazon; additionally, if you also have a dead tree version of the book, this allows you to discount the ebook for people who buy the dead tree version with Kindle Matchbook.
My personal strategy, which obviously won't work for everybody, is as follows:
When I release a book, I price it at 99 cents. After a month, I increase the price to $2.99.
If my first novel (planned but not written) does well, I will extend the series. The first one will stay at $2.99 with frequent discounts and free days, while the others will be priced at $3.99, under the assumption that if you're buying them you've probably already read the first one and decided you like the writing. Only the first book will have free days, to draw in readers; the others people will need to pay for.
The computer science textbook I'm working on will be published in sections, where each section will be a complete book on its own (similar to The Art of Computer Programming, although on a much less grand scale). You'll be able to buy the individual pieces for $2.99 or the collection of all half-dozen or so for $9.99.
And that's my ebook pricing strategy.