I just thought I'd knock together a few tips for when you're looking to buy electrical/electronic goods & associated items. I think a few of the points will have been made here and there within these forums, so this is my attempt at pulling it all together. Any other tips will always be welcome.
First of all, there's a lot of info out there on the web about money saving, but it can be a bit daunting trying to make sense of it all. A good place to start for general advice is Martin Lewis's
Money Saving Expert site. It has a wealth of information on there and can take some time to get through, although there are always plenty of current deals & bargains on the
forums part of the site.
If you know the make and model number of an item you're interested in, then
Price Runner is an excellent comparison site for all manner of electrical/electronic, and other goods. Do remember that you will often pay less than the store price by reserving online to pick up in store. I know that this technique works with Curry's/PC World.
Now for media. There seem to be two lead players in this area, i.e. Amazon and Play.com and it is all too easy to head straight there for what you want, but they are not always the cheapest. Despite its name,
Find-DVD is a very useful price comparison site for all types of media - not only films & music, but also books, mobile phones & services, games, and electrical goods. On the DVD/CD front there is one site that I will especially mention as they are not included in Find-DVD's search engine, and have a habit of being one of the cheapest. I have used
DVD.CO.UK on many occasions and found them to be very quick and reliable (as well as cheap).
Another site worth a mention especially for memory and camera stuff is
www.picstop.co.uk. And for ink cartridges etc.
www.justinkandpaper.com (thanks Uncy).
Looking for mobile phone accessories? The best site I've found so far is
Mobile Phone Crazy. If they do stuff for my ancient Nokia, then you are likely to find bits and bobs for whatever mobie you possess.

Now as for PC stuff itself, there are two sites worthy of a mention.
eBuyer has probably the largest range and most competitive prices. If you're not in a hurry it's worth going for the 'Super Saver' P&P option, as even though it states 'within 5 working days', I've often had items arrive quicker than that. If you spend at least £50 then Super Saver P&P is free, and their customer service is second to none.

The other site I will give a mention to, which has a knack of offering good deals on PC towers, complete systems & miscellaneous peripherals is
Aria Technology.
Last (but very definitely not least, given the theme of this site), if you're looking for routers, modems and related accessories, then
DSL Depot is always a good starting point. They tend to stock discontinued lines at very reasonable prices (and good service in my experience). They are a sister site to
DSL Source.
Happy shopping

I hope this topic will be of use to you all, and I will certainly expand it when I find/remember more related stuff.