Being the mainstream MP3 player that they are, iPods are available from pretty much anywhere these days, they also have a set price rather than an R.R.P., so comparing shops won't find you anything cheaper (unless you go through eBay or something). If you're looking to buy on online, the best place to go would be the
Apple UK store or if you fancy getting your hands on one a little quicker by going to the shops then, like I said, you can get them nearly everywhere. Just pop in to your local Virgin Megastore, PC World, Curries, etc.