Without a doubt Park Chan-Wooks: Vengeance Trilogy Deluxe box set (6 discs).
If you've seen the film's you'll notice the box set actually comes in a copy of the gift box from the film Oldboy (pretty cool already):
In the box set you get a replica claw-hammer (bottle opener)used by Desu in possibly the coolest scene in film history, a copy of the gun blueprints featured in Lady Vengeance, photo cards of images from the films:
Dvd features include:
Sympathy For Mr Vengeance - Double Disc Special Features:
Brand New Fully Remastered HD Feature
Audio Commentary By Director Park Chan-Wook And Actor Ryoo Seung-wan
Jonathan Ross On Park Chan-Wook
Interview With Park Chan-Wook
Production Featurettes
Cast & Crew Interviews
Teasers And Trailers
Widescreen 2.35:1 Anamorphic
Dolby Digital
Languages - Korean
Subtitles - English
Region 2 / PAL / Colour
Running Time 121 Minutes
Old Boy - DVD Special Features:
Brand New Fully Remastered HD Feature
Audio Commentary By Director Park Chan-Wook
Audio Commentary By Director Park Chan-Wook & Cast Members
Audio Commentary By Director Park Chan-Wook & Cinematographer
The Autobiography Of Oldboy (210 Minutes) - An Exhaustive Three-And-A-Half Hour Long Shooting Diary
English Language Dubbed Option
Widescreen 2.35:1 Anamorphic
Dolby Digital
Languages - Korean, English
Subtitles - English
Region 0 / PAL / Colour
Running Time 115 Minutes
Lady Vengeance - DVD Special Features:
Brand New Exclusive-To-Box Set Fade-To-Black-&-White HD Feature
Audio Commentary By Director Park Chan-Wook & Cast
Audio Commentary By Director Park Chan-Wook, Director Of Photography & Art Director
Audio Commentary By Critic Richard Pena
The Making Of Lady Vengeance
Deleted Scenes With Optional Audio Commentary
Character Interviews
Lady Vengeance In Venice
Trailers & Teasers
Widescreen 2.35:1 Anamorphic
Dolby Digital
Languages - Korean
Subtitles - English
Region 0 / PAL / Colour and Black & White
Running Time 115 Minutes