So I just happened to look through some of the old world items, and I found that on at least 3 of my toons servers, no one has old world items for auction in any amount.
For example, on all of the servers I was looking at (different battle groups), there were no Stylin Leather hats in any respect. So I went to look up how much it would cost to make them.
There were no Cobra scales to be found on any of the realms.
So I went and farmed for about 2 hours, got a few, made a few hats. The Cobra Scales were going for over 560g / ea. last check, and the hats were around 7.5k each.
So a reminder, go check the old world mats or use TSM to tell you how much item profit can be had. Some of these old world locations are not farmed much anymore, and since cross-realm wasn't a thing back in TBC days, some of these 20 or less mob areas are prime real estate areas to be farmed just by hopping around.