The Iran visa fee is the money you must pay directly to the embassy and it is different from visa reference code charges. Iran tourist visa fee depends on your nationality or the passport you are using. To give you an idea of the range here is the current prices for issuing Iran visa in Iran embassy in Australia.

And you cannot pay in cash. Most embassies require you to hand in a bank draft covering the fees. Some consulates accept credit cards.

Country	Transit Visa
Australian Passport	68
British Passport	119
New Zealand Passport	170