From Star Trek Online Wiki
Commodities are collections of items that can be purchased from a Commodities Broker or Cargo Vessels in sector space.
 Types of Commodities
 Basic Commodities
|[Industrial Energy Cells]|
 Advanced Commodities
|[Water Purification Systems]|
|[Weather Control Systems]|
 Gamma Quadrant Commodities
- Basic and advanced commodities can be found for a range of prices: Special Vendors (usually 75% EC), Cargo Vessels (75% EC), the base price (100% EC), and Replicator (150% EC).
- Special commodities are always 100% cost, except from the Replicator (150% EC) and Fleet Embassy (75% EC).
- The Quartermaster aboard a Tuffli Class Freighter or Suliban Cell Ship matches the lowest prices available. Access to these can be obtained via various in-game chat channels.
- Ferengi characters receive a 20% discount when buying commodities from any vendor based on a ground map due to the Lobes trait. This includes the Quartermaster above, but not the Shuttlebay console in the New Romulus Embassy (this is probably a bug as per this thread on the official forums, but no progress has been made on resolving it).
- Gamma Quadrant Commodities can be obtained from Duty Officer missions in Cardassian space, or from Special Requisition Pack - Gamma Quadrant Commodities.
- Season 5 increased stack size from 99 to 250.
- In Season 6, the commodities available from Space Traders at 75% are random. If the first one you meet doesn't offer a discount on the needed commodity, try a different trader.