I've been trying to find the exact value of Stamina on items in BC (and eventually Ratings, Resilience, and Sockets if they have a value)

The best method I can think of to do this is trying to duplicate an item in an Item Balancer spreadsheet, I've got the old one written by Hyzenthlei way back when it was still on the R&D forums, and then adjust the value of Stamina until Predicted iValue = Actual iValue. I do this multiple times to find the average Sta Value. If forums are to be believed, the value of Sta is halved (115 as opposed to 230)

This is where the problem I'm running into is, some items result in Stamina = 115 while others have given me numbers as high as 150. Has more than the numbers for Stamina changed, or am I just seeing a large number of underbudgeted items? Several items also appear to be a few dozen Armor short, but that could just be an error in the armor formula I'm using.

Formula's I'm using: http://www.wow.lv/content.php?article.44
Stamina = 110: http://www.thottbot.com/beta?i=2408
Stamina = 145: http://www.thottbot.com/beta?i=162

That's enough of a difference to get an extra 13 Sta on the Leggings if you used 110 instead of 145, or an extra 11 if 115 was used.

isnt 1 agi = 1 str = 1 int = 1 spi = 1 iLvl point in blizzards actual formula?

and 1 sta is 1/3 of the price it used to be so it is like .33 now or something.

Since stamina has been increased by 50%(assumed by of the * items), it's now weighted as 2/3*230~=153.3 (by Hyz's formulation).

That's what I thought at first, but I'm not seeing Sta = 153 value on any of the items.
Take http://www.thottbot.com/beta?i=2408 Murkblood Oven Mits
16 Agi = 3680^1.5 = 223239.8
16 Int = 3680^1.5 = 223239.8
32 AP = 3680^1.5 = 223239.8
24 Sta = 3680^1.5 = 223239.8 (I see what they did there!)

[top]892959.4^2/3

9273/100 = 92.73 actual iValue if Sta = 153.5*

They are iLevel 105 green gloves. 105 * 1.21 = 127-9.8 = 117.2 * .74 = 86.77 expected iValue.

A very large number of items are giving results like this, 5+ iValue higher than expected.

Hm, that's odd. Perhaps they changed the scaling forumla for greens?

Or perhaps they changed the rate at which stamina scales? We're assuming that stamina still gets raised to the 1.5 power, and that could be a term they're tweaking, rather than base cost...

Err, Stamina would be weighted at 115, not at 153. It's just a straight-up halving of the base cost as far as I've been able to tell.

You can simulate this by just plugging in half the listed stamina on the item and see what the iLevel comes out to.

For example: http://wow.tachyonsix.com/itemMaker/?id=1513 - I just put in 12 STA rather than 24.

Calculated iLevel is 105.51, stated is 105. It's dead on target.

The leggings: http://wow.tachyonsix.com/itemMaker/?id=1514 - those work out to an iLvl of 97 or so, stated iLvl of 103. That is a bit low, but not outside of the error of margin that we've come to see in various high-end gear.

(Full disclosure: The above-linked tool is my implementation of Hyz's formulae, but I believe it to be pretty dern accurate).

The Sta/2 doesn't always work though, there's many items (notably Druid T4) that should have 50% more Stam than they are listed with if it was Sta = 115.

Taking a guess at rating value just being Old Value of 1%/Rating at 60 to get 1%, and then rounding a little, the costs would be:
Crit: 230
Hit: 220
Spell Crit: 185
Spell Hit: 310
Dodge: 210
Parry: 180
Block: 260
Defense: 150

I could be completley off base on this, but entering items as (Their rating)/(Rating for 1% at 60) seems to return acceptable results thus far.

Based on these assumptions:
Red/Blue/Yellow Socket: 2000
Meta Socket: 5000

This is simply my best guess based on average results, some items just don't balance out (10 level difference between Resto Druid T4 Shoulders and Feral Druid T4 Shoulders. It just doesn't make any damn sense.