to this day i still dont have the recipe for making heavy leather or thick leather. i knew that if i was a skinner, id have my own reasons for using medium, or heavy leather, instead of combining it to the next level.
it's nice to see 300/300 but it's true, you can spend several hundred gold buying recipes and mats off the AH for that extra 10 points.
on the other hand, since i have a LW and tailor, almost everything is used for tradeskill instead of selling as a raw resources.
so i have to say, while there are some nice upper level recipes which may be profitable, the best way to have a trickle of gold coming in all the time is to *not* have tradeskills and instead just sell cloth, leather, etc.
small gains of gold are good, at least you wont be without money for repairs..ive heard *that* story too many times.