The question is, why?
If I take Blacksmithing, and I ask "what should I take to go along with it?" people inevitably say "Mining, unless you want to spend all your money on reagents."
This doesn't make economic sense. By using your own metal to skillup your blacksmithing, you are not "saving money". You are still denying yourself the income you would have got from selling the bars. You have still invested the time in gathering.
Why don't we see more characters with unlinked gatherer/crafter pairs?
If I was an engineer, the first instinct is to also be a miner. However, there are plenty of people farming metal. If another gathering profession (disenchanting for exampe) could give me the same money/time ratio as the linked gathering profession, then wouldn't it be a better idea to pick an unlinked gathering profession, sell the materials, and then buy the materials you need for your manufacturing profession?
So I could for example be a Miner/Alchemist. I could sell all the metal I mine, and buy all the herbs I need (in general Mining is considered a more profitable gathering profession than Herbalism, so for the same investment of time, I could gather goods with a higher value, sell them, and use the gold to buy more herbs than I could have gathered given the same quantity of time).
Or, in a more mathematical way:
With Mining I can gather trade goods worth X gold in 1 hour.
With Herbalism I can gather trade goods worth Y gold in 1 hour.
Common consensus (whether or not it is true) says that X>Y.
So rather than gathering herbs for 1 hour and using the results (Y gold worth of herbs) to make potions, I mine for 1 hour, sell the trade goods and use the gold to buy herbs. I then use those herbs (X gold worth of herbs, where X>Y) to make potions.
= more skillups/crafted goods for less investment of time.
Obviously there are two factors which haven't been taken into account.
The first is the farming factor. People don't generally go out and gather for 1 hour. People generally gather as they go along. Does Mining still provide more gold than Herbalism in this case? If this is the case then the principle ought to still hold water, only in reverse (take Blacksmithing/Herbalism, sell the herbs and buy the metal).
The other is the economic supply/demand factor - if everybody did this then obviously the price of metal would crash and the price of herbs would skyrocket. However, it seems like there might be a little imbalance in the economy here that could make a tidy little profit for a few enterprising individuals...
Thoughts?
TF