There is no need to spend money to see the marriage license for Joseph Lake and Cynthia Walker. If you go to familysearch.org you can see the image of their marriage license there. Unfortunately, as already stated, licenses that early in Indiana did not include names of parents unless one of the parties getting married was underage and needed consent to marry.
Do you have any additional information on this couple that might help identify them? Years and places of birth? Did they stay in the Marshall County area after they were married? I live in the area and might be able to assist if you can give me some additional info. :)