Was nosing through the Argos clearance and saw this item have an additional special offer of buy 2 & save £5 although the single price is only £2.99 down from £9.99.
When you add 2 it seems to (randomly) subtract an additional £2 for your trouble. Don't know if this is a glitch or an intended % of the original £5 off special offer.
Either way, it's £20 worth of cushions for £3.98..
The additional discount is listed as "Includes special offer saving: £2.00" when 2 are added.