Amazon's Kindle Power Adapter is pretty much an essential buy for anyone with a Kindle e-reader. I bought my second hand Kindle on eBay for cheap, without a charger, and so had to resort to buying one seperately. This charger adapter - the official one - does the trick, no more no less.
The adapter did not come with a Kindle power cable however, which was a pain, and delivery was such that I had to wait a few more days until I could actually use my Kindle. You can charge your Kindle without the adapter, but not without the wire!
Having used my Kindle and charger for about a year or so now I can say resolutely that although the charger was pretty extortionate for what it is, it is pretty hardy. It has been on several holidays with me and hasn't failed on me yet. I suppose it is 'good value' in the sense that it has endured a good year's intense use, but I'm unconvinced the £10 price point is warranted, especially when there are cheaper alternatives. I'm unsure as to the quality of the alternatives but I can't imagine they are any worse quality than the 'trusted' Amazon ones! Furthermore Apple iPhone, iPad, iPod charger adapters do the trick. If you have them spare, you need not bother with this!