What did they say was wrong with the Minnesota Marriage Certificate? I would call the Clerk of Court in the County your Marriage was filed in, and see if they can Rush you one. Then Express it to the Secretary of State's Office for the State Seal. I know the Sec of State has a Web Site
http://www.sos.state.mn.us/
They will Expidite for a larger Fee...
I don't know anything about those companies that say they can get documents. You may be able to deal with it over the phone, just as quickly.
All else fails (I see your in California) Lately NWA has had pretty cheap flights between Lax and Minneapolis if you really want it done right it might be the best if you do it yourself. I know the Sec of State will State Seal a Document while you wait if you get there early enough (when I was there it was around noon or 1 PM as they closed at 3:30).
Good Luck,
Joelpapi