Rare Recipes: Flipping Vs Learning

Rare Recipes : Learn It or Sell It?

So you just found a poorly priced rare profession recipe on the auction house.  Maybe you were out questing or farming and were lucky enough to have a valuable profession recipe drop off of a creature you killed.  Or maybe you got lucky with the contents of a sealed scroll case.  Regardless of how that rare recipe was obtained, what should you do with it? Should you learn it or should you sell it?

My Own Philosophy
I have every profession covered with my factory of alts.  I also am a recipe collector, so the answer is easy for me.  I learn the first copy I obtain and I sell the rest of the profession recipes I accumulate.  Removing the aspect of being a collector, how can you determine whether you should sell the recipe or learn it?

Placing Value On Rare Recipes
The real question when placing value on a rare profession recipe is will I make more profit from flipping the recipe or from mass crafting the item it teaches?  In order to determine whether the items are worth crafting we need to analyze various factors.

What are the materials required to craft the item and what is the value of those materials?
Many times an item can be ruled out as not worth being learned due to the insane material requirements needed for crafting.  Here is a good example of a pattern with expensive material requirements - Plans: Hammer Of Righteous Might:  Khorium Bar (16), Felsteel Bar (12), Primal Might (6), Primal Nether (2). Remember if the value of the crafted item is less than the sum of the materials you are better off selling the raw materials.  Not all rare patterns are worth learning because they are not all profitable investments.

How much will the rare pattern sell for?
Sometimes a pattern may be so rare that you may not have enough demand for the crafted product to sell enough of that product over time to meet the quick and easy profit of just selling the recipe.

Is there a demand for the crafted item and how much will the item sell for?
Lack of demand for the item trumps everything.  An item can be very cost efficient to craft, but if it isn't going to sell there is no point in learning the recipe and crafting the items.  The one exception is, if the item is cheap enough to craft and be utilized in a way other than selling, like via disenchanting.  Maybe it is one of the most cost efficient recipes to learn for disenchanting to create a certain high demand dust, essence, or shard.  So be sure to consider all options for the item.

A Case Study
An excellent example of a very rare pattern that is highly worth learning is for Rich Purple Silk Shirts.  The materials are stupidly cheap and the return on investment is amazing.  The rich purple silk shirt requires Bolt of Silk Cloth (4), Purple Dye, Silken Thread.   These rare craftable shirts sell easily for 15-25 gold each!  It doesn't take many sales to pass up the profit level you would obtain from simply selling the recipe.  Best thing is the demand of these shirts is constant as there are always new characters and new players entering the game. 

I have found similar success selling the Whitesoul Helm as it is a great niche market item.

Can anyone list any other rare patterns that have been worth learning and crafting instead of selling the pattern outright?