Aldi had some folding saws at the same price in last Sunday, and they are much better than the Lidl ones. They have a solid body that won't get full of sawdust and crud, the blades lock properly closed (not just nearly closed so that they can snag on clothes etc, they give you a choice of fine or medium teeth (the latter for green wood) and they throw in a spare blade. Not bad for less than £3, and others have said that they last OK too (from previous years.)
Aldi tend to get more stock of stuff than Lidl, so if you pop in asap you might well still get one.
Oh - they are green too. Green and black. Better than that garish yellow
Ah - I see this has already been mentioned at
http://www.bushcraftuk.com/community/showthread.php?p=261903#post261903, but it makes sense for it to be here, too.
Ben