The "market price" for cocoa at the close of trading was under US$2675 according to ICCO . And the trend is downward.
This price represents what a buyer should expect to pay for bulk-quality cocoa from West Africa with no certification premiums, and is either from the port (FOB), or delivered to the customer. The price does not represent what the farmer gets paid.
In Ghana, the price paid to farmers is set by COCOBOD - the Ghana Cocoa Board. This price is at a discount to the market price does not directly track changes in the market price. Instead, it's a price set several times per year, and is something like a 40% discount to the market price. So, if the market price averaged $3000, the farm gate price would be around $1800. Most cocoa gets traded on the public markets at prices that are directly influenced by the market price. Premiums for quality or certification are most often "marked" to the market and expressed in one of the following forms, "market plus ten percent" or "market plus $XXX dollars).
One major concept behind directly trading is that the buyer gets to work directly with the producer and they negotiate a "fair" price. Usually, this price is at a premium to the market price. So - if the money is paid directly to the producer that generally represents a good deal. However, not all companies report the farm gate price they paid. Notoriously, one NYC-based chocolate maker reported that they paid over 4x the market price for a batch of beans. Looking closely, the price also included all of the transportation and brokerage costs as well as extraordinary costs associated with the transaction.
"Fair" prices for certification are set by the certification bodies. Fairtrade has one, organic has one. Right now, FT is $200/MT and I organic is about the same. Because of the way the system is structured, very few producers ever sell all their cocoa for the premium price, so the average premium they receive can be a negative amount ... they end up losing money producing certified cocoa.
What is fair depends on many factors, and while those factors are pretty much the same from origin to origin, the cost of living from origin to origin is different. So what's fair in Bolivia is not fair in Peru is not fair in Mexico, or Hawaii. Unfortunately, schemes where the premium that is paid is the same around the world exert negative pricing pressure.
So - go do your homework at origin. Find out what's actually being paid and understand what the cost of living is, and more importantly, what the incentives to labor in the farm economy are. In Tabasco, Mexico we learned that even the cacao producers' union - which represents over 25 co-ops and more than 10,000 farmers - is selling cacao at a price that is not sustainable to its largest customers.