What is an option actually worth? It is not like a forward contract, which is easily seen to be fairly priced by arbitrage arguments. There has been research in the equity markets about whether options on indexes are fairly priced but, possibly due to scarcity of data, there is little published work on forex options.
Fortunately, a sufficiently long and wide-ranging currency database is available at Citigroup, with data on more than 30 currencies collected since 1992. The data includes