Zim Bamzabble is the Engineering item vendor at Dragonmaw Port in the Twilight Highlands. Frank Natale is the Alliance version and is located within Highbank. All the high end profession vendors in Twilight Highlands are only accessable after completing the quest line that requires a level 84 character to begin. This limits the number of players that can access these vendors significantly. Most of the items acquired are Bind-on-Pickup, but not the engineering items that Zim and Frank trade. So you can sell these engineering cogwheel gems on the auction house.
All of the new item level 359 Engineering only epic helmets, Bio-Optic Killshades, have a slot for a meta-gem and 2 slots for engineer only cogwheels. These cogwheels can only be obtained after leveling to level 84, completing the quests required to unlock the npcs in Twilight Highlands, then trading the appropriate items to the vendors.
The Bio-Optic Killshades however, can be worn at level 81 and the pattern can be learned at 525 Engineering skill level. This pattern is taught by any of the various Engineering trainers. So you could have the pattern at max skill taught to you and be ready to wear it at level 81. You have to be level 84 to access the cogwheel vendor yourself. See the dilemna? This gives players who have unlocked the Twilight Highlands vendors an opportunity to sell the cogwheels to lower level players who cannot access the vendors themselves.
Engineering Vendor Cogwheel Exchange
List of Cogwheel Gems and Costs:
Fractured Cogwheel- 208 Mastery Rating - Goblin Barbecue
Precise Cogwheel - 208 Expertise Rating - Lure Master Tackle Box
Quick Cogwheel - 208 Haste Rating - 4 x Handful of Obsidium Bolts
Rigid Cogwheel - 208 Hit Rating - Elementium Toolbox
Smooth Cogwheel - 208 Critical Strike Rating - 4 x Handful of Obsidium Bolts
Sparkling Cogwheel - 208 Spirit - Authentic Jr. Engineer Goggles
Subtle Cogwheel - 208 Dodge Rating - 4 x Handful of Obsidium Bolts
Flashing Cogwheel - 208 Parry Rating - Volatile Seaforium Blastpack
Some of the items are rather cheap to craft and others can be found on the auction house. The best thing about this strategy is that you don't need to be an engineer to access the engineering vendor. So look on the auction house for these items to trade in to the vendors for a profit.
Props to Justmytwocopper for touching on this information first. Although in their original post on the New Engineering Market, Mageshadow just recommends the 3 cogwheels that take the Handful of Obsidian Bolts. After further delving into this, I realized that none of the items are very expensive to craft for trading to the vendors. Some can even be found rather cheap on the auction house, since many lower level engineers will dump some of these cheap as they used them to skill up their engineering profession.