Sweeeeet. My dad has something similar happen a week back with a pair of shoes.
Was £20, marked down to £8 so big saving there but when he went to checkout it rang up as 4p. YES 4 pence!! We're guessing a shop person set it up at 4p as something they was going to take home after work but legally they are not allowed to take stock off the shelfs so my dad was lucky in finding them before the person finsihed work hahaah.