As the topic implies. I need help on him, I have reached the chamber of the fayth and I have to start bidding and stuffs but I get 2 or 3 atmost tries before he says: NO DEAL. Can someone help me on this??

From a GameFAQs FAQ...

It's bidding time! First of all, choose the third option, "To defeat the
most powerful of fiends." If you chose this, his asking price will be 250,000
gil. For your first bid, offer half of his asking price, plus one gil. So if
you chose the third option offer 125,001, if he asks for 300,000 give him
150,001. On your next offer raise your offer by one gil. (ex: 125,002). By the
time he offers 205,000, don't press your luck, just make an offer of at least
190k. If at any time you triple or more his asking price, he'll toss in the pot
2 Teleport Spheres, which let you on the Sphere Grid warp to any node activated
by an ally.

I have read that aswell only after I first tried to get Yojimbo a couple of times and it didnt work for me. Further more I came to the discovery that I didnt pick to beat the strongest of foes option but the 1st option I think (srry cant recall what it was). So if someone can help me plz do so ^_^.

How much are you offering him? Like Vivi said, I wouldn't go much lower than 190K.

I finally got him thx for the help guys.