Listmania!
Great Books On Logic
Arguing WellArguing Well by John Shand
Buy new: £13.99 / Used from: £4.68
I completely disagree, but it's a good place to start.
The Ways of Paradox and Other EssaysThe Ways of Paradox and Other Essays by WV Quine
Buy new: £21.80 / Used from: £9.94
A good collection to dip into.
From a Logical Point of ViewFrom a Logical Point of View by WV Quine
Buy new: £14.14 / Used from: £11.24
Easy to understand, great analysis.
Conjectures and Refutations (Routledge Classics): The Growth of Scientific KnowledgeConjectures and Refutations (Routledge Classics): The Growth of Scientific Knowledge by Karl Popper
Buy new: £9.48 / Used from: £6.99
An expert in Logic, great on paradoxes.
Logic and Language: 1st SeriesLogic and Language: 1st Series by Gilbert et al Ryle
Buy used from: £1.80
Ryle is a must.
Beginning LogicBeginning Logic by E.J. Lemmon
Buy new: £39.68 / Used from: £6.78
Dull, but you must learn formal logic.
Bluff Your Way in Philosophy (Bluffer Guides)Bluff Your Way in Philosophy (Bluffer Guides) by Jim Hankinson
Buy used from: £0.05
A great place to gain a general knowledge.