Hi,
I made myself a clever spreadsheet that's helped me out no end.
It takes raw mats gathered per/hour and then compares that to the value of the various shuffles and crafts available from that. From there I can say that per hour, from my gatherer bot I can obtain 600 Ghost Iron Ore (relatively safely, my own profile -based on no one elses).
From there I can say 600 x Ghost Iron Ore is worth approx 1,446.00 Gold on my server.
The maximum value of that mat is 8,857.14.
However demand sees that I most often sell within a spectrum of 4,125 to 4,320.00.
So at a conservative estimate (taking in AH cut and extra time) I'd say that I yield 4,000 Gold per hour.
That's one account, GatherBuddy2, shuffling by hand with max level alts and their professions. I suppose it would be a lot higher and I could navigate the supply and demand issue by automating the botting somewhat with the TSM profile/plugin floating around the forums and/or the Saleman plugin. But I like my custom spreadsheet and I update it daily, comparing the markets via TheUndermineJournal.
The problem however, is sitting on stockpiles... even on my busy Realm demand is ok the supply is sky-rocketing leading to prices crashing in the last 30 days. Certainly there is enormous value in understanding your Realm's biggest raiding days and how that effects your demand.
Now... if you want to make dozens of thousands of gold per hour... then you need to be in the business of boosting. But that's another story! *wink*