Today only, until 7 pm ET, Amazon.co.uk offers the Harry Potter: The Complete 8-Film Collection on Blu-ray Disc for $25.65 (£16.99). At checkout, the price drops to $21.37 (£14.16). With $4.65 (£3.08) for shipping, that's $2 under our April mention and the lowest total price we've seen. (It's a current low by $14.)
This Blu-ray set is region-free, and the films themselves will play on US Blu-ray players, but note that the extras and special features may not.