Calm Lands go to the bridge in the far northeast cornor of the map and head to the bridge leading to Mt. Gagazet, (but moroon, don't go to Mt. Gagazet!) instead, go into the gorge below, (aAaAhHhH sCaRaY! I See DEAD PEOPLE!), oh anyway.... and head into the Cavern of the Stolen Fayth left of the Save Sphere.(not the save sphere on the map below brain dead!).......

Go on into the cavern (lions and tigers and bears....oh my!) until you encounter the spirit of a dead summoner. This summoner will now call upon the duder Yojimbo. This aeon is popey stronged out, but his magic defense stinks! So hit him with spells like Firaga. Afterwords, you'll reach a teleport pad where you can enter two hidden chambers that contain a Flexible Arm, an MP sphere, and two (that's right two) X-Potions! (see map below for details).

Now this is where you hagglers get to play and have fun.... ok, in the main chamber where the teleport pad is, teleport into the chamber straight ahead. Here Yuna will call upon Yojimbo when the spirit appears he will offer his services for a price. He will offer his lowest intial price if you choose the option "To defeat the most powerful enemies," for your first bid (going once, going twice, SOLD!) offer half (THAT'S RIGHT, HALF!) of what he's offering, plus 1 Gil.

So if he offers 250,000, you (the super duper haggler) offers 125,001, and like after his next offer add another gil to your offer, and like by the time he offers 205,000, he will accept offers below 200,000, but not much lower cuz' he's a meany head. So be careful, I got him at 198,000 gil so just keep that in mind! When he accepts your puny offer he will join your twisted demented team of scary aeons! To infinity and BEYOND!

Chamber of The Stolen Fayth Map Guide.