There are multiple sources of Primal Spirits in World of Warcraft, some of which are free so why would you need to work out a price for them? Well, Primal Spirits are one way of increasing your supply of the bind on pick up crafting materials like Burnished Leather or Hexweave Cloth which are used to craft the highest quality armor and weapons as well as the item upgrade essences. You can also exchange Primal Spirits for the Sorcerous Air, Water, Earth and Fire that you need for crafting as well as Savage Bloods.
If you are going to craft any of the high end gear or upgrade Essences, you need to know your base crafting cost so you know exactly how much you can sell it for and still make a great profit.
Sources of Primal Spirits
The main free source of Primal Spirits is the gathering professions - you will occasionally get them when mining, herbing, fishing or skinning.
There are some missions for your followers which reward Primal Spirits - I'd count these as a free source too.
Another 'free' source of Primal Spirits are the various caches, bags and also the mine carts in your garrison mine.
Garrison Traders will sell you Primal Spirits in exchange for raw materials. There are five possible traders who can turn up in the entrance hall of your Level 3 Garrison Town Hall - the fur, ore, herb, dust and leather traders. Each Primal Spirit will cost you 5 raw materials - which material will depend on which Trader is visiting that day.
Calculating A Price For Primal Spirits
Primal Spirits are only used in a couple of high end crafting recipes - these are the recipes that allow you to make a BoP crafted material without a cooldown but as they give only 1 BoP material, it is an expensive way to get extras.
So the main use for Primal Spirits is to pay for BoP crafting materials, Savage Blood and the various Sorcerous elements. But before you start exchanging like crazy, you really should check out the prices of the raw materials and Savage Bloods on the Auction House.
If you cost the Primal Spirits based on the daily Trader, you will have a possible 5 different prices. You can take an average of these to calculate your Primal Spirit cost or you can set yourself a maximum price for bulk buying the raw materials and use that as your basis.
For example - the Traders accept 5 each of true iron ore, draenic dust, talador orchid, sumptuous fur and raw beast hides. If each of those has an average price of 2 gold then each Primal Spirit is costing you 10 gold (5 mats x 2gold). That's not going to be the case usually though - each material will have a different average price so work out 5 x each price, add them all together then divide the total by 5 - that will give you an average price to use.
Or you could fix your raw material buy price at 1.50 gold and only buy bulk raw materials under that so your maximum cost for a Primal Spirit will be 7.50 gold (5mats x 1.5 gold). This is where your bargain basement shopping skills come into play!
Trading Up Primal Spirits
OK, so you have a price for your Primal Spirits now but what are you going to do with them? The main use is to buy BoP crafting materials from the Primal Spirit Trader in your Garrison but you still need to check the Auction House for prices. Obviously you can't buy BoP crafting materials on the Auction House so you need to calculate the cost based on raw materials costs.
Each BoP material costs 5 Primal Spirits and as mentioned earlier, each Primal Spirit takes 5 raw material. This means that a single piece of Burnished Leather or Hexweave Cloth for example, has an equivalent value of 25 raw materials (5 to trade per Primal Spirit x 5 Primal Spirits to trade for BoP Material).
So in the examples above, a single BoP crafted material will cost either 50 gold or 37.50 gold, depending on how you calculated your base costs.
The thing is though - each piece of BoP crafted material can also be obtained via Work Orders in your Garrison and those only cost 5 raw materials. So why would you spend 25 raw materials via the Traders to get the same crafted material? The truth is, you don't need to but as the Work Orders are time limited, you may find that you are selling your crafted gear faster than you can get the materials via Work Orders.
The same basic calculations apply for buying the Sorcerous elements or Savage Bloods. Sorcerous elements cost 15 Primal Spirits so that's 150 gold or 112.50 gold (15 x 5 raw materials=75 raw mats) which is a crazy price! My Auction House has Sorcerous elements ranging from 25-45 gold so I won't be using Primal Spirits to buy those any time soon!
Savage Bloods cost 25 Primal Spirits from the trader so the equivalent raw material cost is 250 gold or 187.50 gold (25 x 5 raw materials = 125 raw mats). That's a bit better but not much. Savage Blood sells for between 180 gold - 270 gold on my server so there's very little profit to be made by selling Savage Bloods bought with Primal Spirits. You can also get Savage Blood from your Barn but unless you have loads of Barns in full production, you will probably need to buy Savage Blood at some point.
Calculating Cost of Crafted Gear
Most of the epic item level 640 crafted gear uses 100 of the BoP crafted materials and a few bits of other basic raw materials. It's fairly easy to calculate the base cost of crafting these as 100 x 5 raw materials if you get all your BoP material from work orders. If you do use the various Traders to buy BoP materials then the calculations above will set the price for your epic item.
These epic gear items are all upgradeable though and this is where the Savage Blood price comes in. Each upgrade from level 1 to 4 will cost 70 BoP crafted material, 15 Savage Bloods and 15 Sorcerous elements to make the upgrade Essence. You can upgrade the crafted gear without equipping it so depending on the prices on your Auction House, the best profit may come from selling an upgraded item rather than the base item.
You can also sell the Essence itself but again, check the prices on your Auction House and watch your base costs!
With so many ways to convert raw materials, garrison resources and Primal Spirits to BoP materials and Savage Blood, fixing your crafting costs is always going to need to be flexible. But it will give you a baseline below which you just don't craft or sell your items. If you feel like Primal Spirits and Savage Bloods are 'free' because you get them while your doing other stuff in game, then you will be seriously eating into your own profits by selling the final product too cheaply. You don't need a huge spreadsheet to track these prices to the copper, just make sure you are aware of the costs of crafting so you don't underprice your gear on the Auction House.
I hope this makes sense - it's tough to explain in writing how my brain works sometimes! Please let me know if I've messed up somewhere or if the prices on your server are way different. I'd be interested to know how do you calculate your prices too.