This Minnie Mouse fancy dress has been reduced from £12.50 to £6 at Tesco instore. It includes the dress and a headband with ears and a bow.
I cannot find it online but Tesco direct have a similar one for £13 (without the headband).
I found this is the St. Helens Extra store. There were plenty left. They hadn't been marked down, only when scanning did I find they are reduced.
The barcode ends in 167387. Hope it helps :)