When you are talking about £450 phones, whether that be an iPhone 4 or some other phone (the Samsung Galaxy S II has been priced at £600+ at pre-release), you are talking about the latest technology with expensive components and companies wanting to recoup R&D costs, so it isn't really overpriced. Technology generally has a short optimal value life, which is why you get prices reduced after they've been out for 6 months or a year. If you wanted a top of the range games machine then you may be looking at £2000, yet if you went for a spec that's been out 18 months but able still to play latest games you could half or even quarter the price, so mobiles are not alone.
If you use your phone for talk/text with some web browsing then there's a wide selection of phones, that luckily for you, have depreciated to an extent that they are cheap-ish. Luckily those who want the latest tech are willing to pay for it and those pushing the boundaries are able to charge enough to keep pushing the limits. Dual core androids are coming out, and I'm sure iPhone 5 will blow people away. Next year we could be on about quad-core mobiles and get to a stage where the only difference between a mobile phone and a laptop is size.