As a sales assistant in one of these retailers I know that we get asked for this a lot. The trouble is, that the margin on products we sell is so low these days it just isn't worth matching online prices. Forgot not, that if you have a problem with one of you're products that you've purchased online, you don't have the luxury of coming into a branch and having us look after you, ie swapping it there and then in some cases, organising the repair for you or perhaps showing that it may be user error.