From what I gather under the article, due to Delphine disbanding, the game's source code for each system became abandonware, and thus under a GNU public license, is free to distribute. From here, people are taking the bests from all versions, and putting them together under a PS2 format, to be freely distrubuted on the web.
So don't worry about paying for it!
All you have to worry about is the actual daunting task of trying to MOUNT the actual game to a DVD that can PLAY on the PS2 without fucking up along the way.
EDIT: And from the looks of things, I don't think much editing was done to ANY of the origanal source codes, meaning all they basicly did was mash ten source codes together, and modify it with different controls. So really, there is no definate chance the fucking thing is going to work even IF you mounted and copied it successfully.