Stuck...quest for Ultimate Weapons.

Okay, I'm at the point where I'm about to head inside Sin. But before I do, I decided to use the airship and go around looking for all the Ultimate Weapons. So I read a FAQ guide somewhere, and it told me to go to the Calm Lands and obtain a chocobo from the stationary chocobo rider there (yeah, I know, it's the first step. -_-) Where exactly is that person? I don't seem him/her anywhere at the shop in the middle of the plains. Am I looking at the right place? Could the problem be that I'm at the point in the story where he/she is no longer there? I also found a chocobo roaming freely in the plains just northeast of the shop, but I can't mount it.

Can somebody help me? I'm clueless as what I'm supposed to do.

She isn't always in the same place. Sometimes she's sitting on her chocobo just outside of the travel agency in the middle of the Calm Lands. Sometimes she's on the ledge where you enter the Calm Lands from Mancalia Woods (I usually find her there). And at one point in the game I think she is on the edge of the cliff in the north western part of the plains.