The Korg Legacy Collection synthesizers are individually available now on Korg User Net. A few of them are real classics. The MS-20, Polysix, Mono/Poly, M1 and Wavestation are sold for $50 (€37), the MDE-X for $20 (€15).
When you would like to purchase all vst instruments of the Legacy Collection, then the Special Bundle is the way to go. This bundle contains all plugins and costs $200 (€147).
Update: the registration on Korg User Net doesn’t work at the moment due to server problems. If you don’t have a Korg product you can register by clicking on the Buy button (two times), one of the KVR Audio forum member mentions. After filling in the registration form you should see the link to the download section for registered users.