
Ansel Krulwich |

Nodachi: 60 gp
Cold Iron: +60 gp (doubles the cost of the weapon)
Masterwork: +300 gp
+1 enchantment: +2,000 gp plus an additional 2,000 gp because of cold iron
Keen enchantment: +6,000 gp (cost of an additional +1 enhancement for a total of +2)
Holy enchantment: +24,000 gp (cost of an additional +2 enhancement for a total of +4)
Total: 34,420 gp
Edited for clarity.

DM_Blake |

I have no idea the price of a no-dachi, I didn't find it searching the SRD.
Whatever the price is, Cold Iron doubles that price. Also, Cold Iron adds a one-time 2,000 gp cost for enchanting weapons made of it. Masterwork is required for enchanting, that costs 300 gp.
Keen counts as +1 and Holy counts as +2 and the weapon is +1, so the total equivalent enhancement is +4. According to the book, that's 32,000 gp.
So:
32,000 + 2,000 + 300 + 2x whatever the no-dachi costs.
You pay that if you hire an NPC to make it, but if you make it yourself or have a friend make it who only charges you the cost of materials, you could pay half that total.

DM_Blake |

No, Ansel, I am pretty sure that's not how it works.
According to the Core Rulebook under Magic Weapons:
"A magic weapon is enhanced to strike more truly and deliver more damage. Magic weapons have enhancement bonuses ranging from +1 to +5.
...
Some magic weapons have special abilities. Special abilities count as additional bonuses for determining the market value of the item, but do not modify attack or damage bonuses (except where specifically noted). A single weapon cannot have a modified bonus ... higher than +10."
According to this, you add all the enhancement bonuses together to get one combined bonus (in the OP's case the bonus is +4) and then consult Table: Weapon Pricing by Bonus to see the price of the weapon (a +4 weapon costs 32,000 gp).
I don't think Cold Iron doubles the cost of enchanting the weapon, just making it. Assuming you're right about the 60gp, that means the sword 420 gp to make it both masterwork and Cold Iron. Cold Iron does cause that one-time cost of 2,000 gp to enchant it.
So using your price for the no-dachi, we end up at:
32,000 + 2,000 + 300 + 120 = 34,420 gp base price.
Edit: Ah, now I see you edited your post. Still seems like the hard way to calculate it - much easier to just add +1 +1 +2 = 4 and look up that price (or if you like math, the formula is bonus ^2 x 2,000 gp, so 4^2 = 16, 16 x 2,000 gp = 32,000 gp, exactly as the chart indicates).

Ansel Krulwich |

I think you missed my edit incorporating Jeraa's clarification. I described it as "doubling" the enchantment cost since 2000x2=2000+2000 but while that's technically correct, it's misleading.
You explain it as the summarized cost and I explain it as the incremental cost. We arrive at the same number in the end.
Edit: Yeah... all that. I've had to explain it both ways to different people. Math is hard.