Currently, most Catatrade goods are relatively expensive due to exceedingly high demand to level crafting professions. This much should be obvious and common sense.
How can we use this to our advantage?
Many, many people are buying materials and posting up modified items on the AH. The best example would be (of course) JC, where a crafter buys an uncut gem for 40-150g then posts the cut version up at a significant price cut to recoup some of his loss. This is good news for end-users leveling and even better news for us.
The other example of this phenomenon is with Enchanting. Enchants are being put on scrolls with material costs in the hundreds of gold, yet the scrolls are being posted for less than 15g (less than 5g in some cases!) on most servers. Examples of this are numerous:
Enchant Cloak - Critical Strike
Enchant Cloak - Intellect
Enchant Boots - Major Agility
Enchant Gloves - Exceptional Strength
Enchant Bracer - Dodge
I plan on snatching a few of these up at sub-10g each and holding them for roughly two months when prices should have stabilized off. I expect to get about a 60% profit on most of these, posting them around 16-20g, with the exception of Gloves - Strength and Boots - Agility. Going to push for around 40 on those.
Returning to JC, however. the example I have discovered is quite simple:
Carnelian Spikes
These fist weapons get crafted by JCs leveling their skill in a batch of 8-10 since--on some servers--three Carnelians are cheaper than two Hessonites (both are bracketed to the same portion of leveling JC). Hessonite's (and Nightstone's) price, at the moment, is kept artificially high due to JC needing around 40 Hessonite or Nightstone to level JC by making rings or necklaces from 475-495.
Hessonite Band
Nightstone Choker
These items are the ONLY way to level JC from 475-495 with guaranteed skill-ups, so these gems' prices will usually be fairly high in comparison to other green-quality Cata gems.
Therfore, this item will usually be the cheaper option for most JCs to level about 10 points with. This means JCs will purchase/prospect three Carnelians and make these weapons, then post them on the AH cheap to recoup some of the loss.
In fact, according to TUJ's pricing, the average on most servers tends to sit in the 45g to 70g range for the Carnelian Spikes, well below the material cost.
They do sell to alts and whatnot since they are very strong weapons in their own right.
Why is this particular item so good for us?
Wowhead disenchant data is actually INCORRECT on this item since item disenchants were hotfixed on US servers. This item no longer DEs into Lesser Celestial Essence but GREATER instead due to its 317 ilvl.
Typical DEs are 3-5 Hypnotic Dust, 2 GCEs or 3 GCEs.
Let's do the math.
Typical TUJ prices for Hypnotic Dust: 18-37g
Typical TUJ prices for Greater Celestial Essence: 45-80g
Typical TUJ prices for Lesser Celestial Essence: a little more server-dependent, but 11-30g each seems about average
This means that even buying Carnelian Spikes at 100g apiece is still going to turn a profit on most servers, particularly on triple disenchants.
I've bought roughly 30 in the last 12 hours. These are my results:
3x GCE
3x GCE
3x GCE
2x GCE
3x GCE
5x HD
3x HD
5x HD
2x GCE
2x GCE
3x GCE
3x GCE
3x HD
2x GCE
2x GCE
5x HD
4x HD
5x HD
2x GCE
3x GCE
.....
and so on.
So, buy the Spikes cheap, DE them, sell the resulting mats (or hell, use them to level Enchanting). Money in the bank for next to no effort.
Bonus round: buy Elementium/Obsidium, prospect, sell all other gems except Carnelian, craft Spikes, DE, sell Enchanting mats. Hooray, ore shuffe!