These lie detector kits at Maplin seem like pretty decent value at £7.99 (reserve and collect or add £2.99 for delivery). Just the job if you are on the look out for interesting stocking fillers or Christmas novelty gifts.
Product Information :-
Demonstrates the basic principles of lie detection: the change in resistance of skin in the presence of perspiration
Requires 1 x 9V PP3 battery (Order Code: L46AL)