On a genealogy research trip to Madison, Morgan Co, GA in the spring of 2010 a number of old records relating to the Prince family were found in the archives building beside the courthouse. I found a map showing where Daniel & Sarah's house was. I am almost certain I know where they are buried, at least the cemetery, but not the specific spot there (unmarked). A survey of the property prepared in 1869 is located at the bottom of this page.
The county seat of Morgan county is Madison, GA. It is a very popular town with tourists, as the old town is well kept, with numerous outdoor eating areas and antique stores. The old probate records are kept in a building beside the courthouse, and is only open a few days a week, so be sure to call before making the long drive. The people who run the archives are VERY knowledgeable about what records are there, and are extremely helpful.