Amazon UK has X-Men Quadrilogy:
X-Men: The Last Stand
X-Men Origins: Wolverine
Blu-ray for £10.99 - £1.83 instant savings at checkout + £3.08 shipping = £12.24 (or ~USD $19.91).
According to Blu-ray.com users, this Blu-ray set is Region A (US) and Region B (UK) encoded and will work on US Blu-ray players.