Bestbuy currently have an iPod dock for sale for £19.99 (£10 off the RRP of £29.99) with free delivery (or reserve and pick up instore).
It seems like a pretty good price as it has a built in alarm clock, charges your iPod and can also be used as a speaker dock. It also comes with a remote and can be powered by 6 x AA batteries as well as via. the mains (mains lead is included).
Reviews are a bit hit and miss and it seems it doesn't charge iPhones (hence why I've put it as an iPod dock and not an iDock, although I tested my girlfriend's iPhone 3G on it and it seems to charge it fine? Not so sure with later models of the iPhone...) and some people have had issues with the clock losing time, but it seems a pretty good package for under a score delivered! I've had a look around and it seems to sell for between £25 and £30 everywhere else.
Also, if you're with quidco you can get 14.89% cashback bringing the total to £17.01 delivered - not bad!