This is a fascinating market that has been around since the start of the Darkmoon Faire. I only learned about it a couple months back when a user ( duck ) from the consortium forums posted it. I simply love making gold with this method.
You can make thousands of gold from this method and you're only having to invest a couple thousand. Last time I did this method I put in roughly 500g and walked out with about 20,000g in loot from patterns/greens. After everything sold I was sitting on a nice hefty pile of 21,500g.
The way the method works is you buy Dense Stone, use a blacksmith ( or your own ) to turn that into Dense Grinding Stone which you will then turn that in into Kerri Hicks who takes 8 Dense Grinding Stones for 20 Darkmoon Faire Tickets. You then turn those tickets in for bags that can have varied loot but most importantly a ton of rare & expensive patterns.
There are three different bags that you can turn in the tickets in for, I'll list them below and their noteable loots.
Minor Darkmoon Prize - Item - World of Warcraft [ 5 Tickets ]
Razor's Edge - Item - World of Warcraft
Feet of the Lynx - Item - World of Warcraft
Ranger Bow - Item - World of Warcraft
Blackfang - Item - World of Warcraft
Rakzur Club - Item - World of Warcraft
Sentry Cloak - Item - World of Warcraft
Lesser Darkmoon Prize - Item - World of Warcraft [ 12 Tickets ]
Plans: Mithril Shield Spike - Item - World of Warcraft
Pattern: Guardian Belt - Item - World of Warcraft
Schematic: Craftsman's Monocle - Item - World of Warcraft
Pattern: Comfortable Leather Hat - Item - World of Warcraft
Midnight Mace - Item - World of Warcraft
Black Duskwood Staff - Item - World of Warcraft
Greater Darkmoon Prize - Item - World of Warcraft [ 40 Tickets ]
Pattern: Mooncloth Leggings - Item - World of Warcraft
Schematic: Sniper Scope - Item - World of Warcraft
Plans: Radiant Belt - Item - World of Warcraft
Plans: Dawnbringer Shoulders - Item - World of Warcraft
Six Demon Bag - Item - World of Warcraft
Schematic: Lifelike Mechanical Toad - Item - World of Warcraft
Plans: Whitesoul Helm - Item - World of Warcraft
Formula: Enchant Gloves - Riding Skill - Item - World of Warcraft
Pattern: Star Belt - Item - World of Warcraft
When opening the bags you'll receive a ton of greens that you can sell anywhere from 10-25g ( I sell all of mine at 25g/ea and relist every 48 hours.. I rarely get any of them back unsold ). By selling the green you're actually paying for the price of the Dense Stone which is just simply great, it makes the rare patterns/rare gear 100% profit.
I suggest you guys go try this out, it's an easy way to turn 500g into 10k+ gold, even more depending if you get a rare pattern worth 5-10k+. What do you have to risk? Go ahead an try it out!
source: Just My Two Copper: How to Turn 500g into 20k+ Gold - Wow Cataclysm Gold Guide Blog