I've been looking for a little pen tool to do a bit of metalwork and found this from Halfords for a good tenner less than any equivalent items elsewhere. It's similar to a Dremel tool (i.e. it's a small drill with lots of attachments for metal/woodwork and small bits of DIY) and comes with a pretty decent range of accessories.
It's worth noting that most of the supplied accessories are varying shapes and sizes of engraving/grinding tool, but along with that there are cutting discs, polishing and sanding wheels and a few drill bits, so a fairly versatile set.
One thing to bear in mind when ordering from Halfords is that their online stock checker is not very reliable - according to the chap in my local store it's due to their website and warehouse using different computer languages with the end result that something showing as in stock on their website may not actually be in store (And vice versa)