It's nice to have options.

UK-based publishers like Penguin and Bloomsbury have begun discounting books on their own websites, incentivizing customers to buy straight from the source instead of through Amazon.

The move parallels a price flexibility trend among retail vendors concerned about the US economy. It may also be a quiet commentary on Amazon, which first made its mark by enabling people to buy heavily-discounted items online.

These days the discounts are unexceptional. A boxed set of 20 Penguin Epics that retailed for £100, for example, is £98.64 on Amazon. The set is now £55 on the Penguin site.

Brick-and-mortar booksellers are also stepping the game up online, providing rewards perks and heavy discounts that make Amazon's rates look even more average.

Amazon could retaliate by interpreting online publisher prices as the recommended retail value, then slashing its rates accordingly and taking its cut based on that figure, said The Times. But publishers say this would ultimately drive prices higher.

And the giant isn't entirely on the defensive. Early this month Amazon debuted a mobile shopping service that lets people buy discounted items from their phones, even while they are in stores.

It is also moving aggressively in online music, writes ZDNet. Since the launch of its DRM-free music store in September, it's been proclaimed the second-largest online music retailer by USA Today. It also developed a means for people to earmark MP3s for purchase in games like Grand Theft Auto IV.