So there is a little debate among knitters and Harry Potter fans about which is the 'correct' or 'true' pattern for the Hogwarts House scarf... in the first movies it was alternating blocks of house colours and then in the Prisoner of Azkaban they changed the design to thin stripes of one colour on a background colour... well I think the cover of the Philosophers Stone book sorts this problem out as Harry's scarf on it is clearly alternating blocks of colour and who cares about the movies anyway...

Sure you could buy an official Harry Potter merchandise one for $45 dollars... or you could spend $10 on yarn and a pair of knitting needles and kill approximately 30 hours of boredom...