Dark Matters aren't that hard to come by as you can earn other rewards as you work for it.

For me, I battled One Eye for Triple AP weapons and selling all those extra one. Before I knew it, I had Triple AP weapons for everyone and a lot of Dark Matters. Not to forget a lot of money too from selling all those extra weapons.

As for Chocobo Racing: http://forums.eyesonff.com/showthread.php?t=69000