Pricing items with specific resistance bonuses to saves

[Yora]

The magic item pricing chart only includes the price for a resistance bonus to all saving throws, which is bonus squared times 1,000 gp.

Now I want to make custom items that provide a resistance bonus only to Reflex saves, or only to saves against poison. What do you think would be a good price?

Is having a bonus to only one save worth more or less than one third the price for having a bonus to all three?

I am thinking of X * 250 gp for either Fortitude, Reflex, or Will saves, and X * 200 gp for more specific saves like vs. poison, vs. fear, and so on.
But that's really quite cheap and could be seen as a kind of cherry picking, so there would also be good arguments to make them twice as expensive.

[Lobo Apache]

In my humble opinion to give either Fortitude, Reflex, or Will saves I would have it be something like X* 333 (one third) and for poison, fear, ext I would do the 200 b/c those are more specialized and rarer opportunities to use them.

[Zahir ibn Mahmoud ibn Jothan]

In my "magic item pricing" spreadsheet, I backed my way into this by using an item from Rise of the Runelords that does exactly this, it has an AC bonus, a stat bonus, and a specific save bonus. Since 2 of the 3 are known quantities, it was pretty easy.

One could argue that certain specific saves are worth more or less.

The item in question had a very specific save, not just like Wil or Ref, it was vs. a specific damage type/source.

Sorry for the ambiguity, just trying to avoid spoilers.

[Jeraa]

I would suggest that a bonus to a single save should cost (bonus squared) x 250gp. That makes the pricing would line up with the normal Cloak of Resistance if you use the "Multiple Different Abilities" additional price multiplier (additional abilities beyond the first cost 1.5x normal).

+1 Reflex save: 250gp
+1 Fortitude save: 250gp x 1.5 = 375gp
+1 Will save: 250gp x 1.5 = 375gp
Total: 1000gp
Normal +1 Cloak of Resistance: 1000gp

+2 Reflex: 1000gp
+2 Fort: 1500gp
+2 Will: 1500gp
Total: 4000gp
Normal +2 Cloak of Resistance: 4000gp

Its just like how the various ability score boosting items have a version with multiple enchantments in a single item.