I needed a couple of mouse traps for my Gran, I called in at B&Q and found these at half price (down from £4 to £2 for a twin pack).
These traps are excellent, they're much less fiddly than traditional wooden traps, easier to set due to the better leverage. They're also less likely to go off (and make you jump) as you set them. Easier for my Gran and her arthritic fingers to set too.
B&Q also do a twin pack of their own brand "Advanced" traps with a very similar design, but at twice the price of these.