Amazon and eBay are two places to buy printed English/Farsi and Farsi/English dictionaries. There are also free websites, such as Farsidic.com and Dictionary-Farsi.com as of 2015, that provide online dictionary and translation services.
Amazon and eBay sellers offer new and used Farsi dictionaries at a variety of prices. Both sites have a rating system to increase the security of purchases; higher-rated sellers have a higher chance of being trustworthy. After a buyer purchases a Farsi dictionary from either of these sites, the dictionary arrives by mail.
Online English/Farsi and Farsi/English dictionary sites offer free translation as well as usage examples and educational games. The online translation may be less reliable than a printed book because many sites are written by users. However, if a quick translation is necessary, free online websites provide instant answers.