Who wants a certified copy? Are you meaning for an initial filing of the I-129F?
From USCIS
14. USCIS no longer routinely requires submission of original documents or "certified copies." Instead, ordinary legible photocopies of such documents (including naturalization certificates and alien registration cards) will be acceptable for initial filing and approval of petitions and applications.
At the discretion of the officer, original documents may still be required in individual cases. Please be advised that USCIS no longer returns original documents submitted with the exception of Certificates of Naturalization, Forms I-551, Permanent Resident Card, Forms I-94, Arrival/Departure Document, valid passports, or those specifically requested by the officer. Such documents will be returned when they are no longer needed.
http://www.uscis.gov/graphics/fieldoffices/scnational/A certified copy is one that you get from the issuing body that holds records.