There's a huge difference between converting a game to run in higher resolution (the Ubisoft packs, the Sony packs) and actually remaking the game. From what I saw, both this and Halo took a lot more effort than something like the HD packs that are cranked out by other studios. This is closer to the Flashback XBLA release than the Beyond Good & Evil one. I think $30 is reasonable for what is essentially a new game styled after an older one.
CEA was only a graphical upgrade. (with the addition of terminals and skulls in the new graphics mode)
The game assets and stuff were from the PC version, just the new graphics mode had redone textures and such.