You may "import" into the Russian Federation up to $10,000 (or equivalent) and "export" up to $3,000 without declaring it at the customs. If you export from the country a sum of money over $3,000 and up to $10,000 it must be declared on departure.
If you are exporting from the country a sum of over $10,000 you must provide documentary proof that you either imported it into the country or have legally obtained it whilst in the country.
If you complete a [declaration] form to state that you are bringing in more than $3,000 you must ensure that it is stamped by a Customs official at your port of entry or it will not be valid. [declaration] forms are freely available at the ports of entry.
If you cash travellers cheques, or obtain money from a bank, make sure you keep all documents as proof. Please note, that travellers cheques may be difficult to cash and be charged at a premium, outside of Moscow and St. Petersburg. Sterling may also be difficult to change so we recommend you take either US dollars or Euros.
NOTE! If you fail to complete a declaration form on arrival or to get it validated by Customs officials your foreign currency and non-declared items may be confiscated when you leave Russia and you may be fined.