Amazon.co.uk offers The Ultimate Gangster: Class A Selection Box Set on Blu-ray Disc for $15.03 (£9.94). During checkout, it falls to $12.52 (£8.28). With $4.66 (£3.08) for shipping, that's the lowest total price we could find by $23. This 5-disc set includes American Gangster, Carlito's Way, Casino, Public Enemies, and Scarface.
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.
Note that it's now expected to ship in one to two weeks.