Which components are you missing? Each one of the level 100 items is a rare drop when you break each of those characters at a... 1% or so drop rate I believe.
There's a sort of cheapish way to get them to drop more often, but at least it's far quicker than trying to grind them out... I did it in the Jap version, and don't feel like doing it here. I'll put it in spoiler tags though just in case.
[spoiler]The best way to do it, I've found, is to equip a moonrise and two sunrises. The rest of your accessories should be booster accessories that you know will be in effect right at the beginning of the match no matter what. Once that's done, equip Manual Odin. Start the battle (in Quick Battle) and use Odin right away. If he doesn't work, or if you don't get the Gold Star drop, just pause the game and go to retry. It won't have any adverse effects to your stats I don't think, since it will be like you never used the summon or got any exp. Keeping trying until you get that Gold Star, then kick his/her ass.[/spoiler]
The other half of the ingredients are in the Invincible course... either that, or trade them for megalixirs (which you also get from the Invincible course).