Anyone know of a good strategy for implementing a radio button into a DataGridView cell that I can read/write values to/from?

Presuming that you haven't already found the answer, what I'd recommend is making that column a template column in the edit columns section of the GridView. Next, select Edit templates, and select the edit item template of the column you just turned into a template column. This gives you access to modify how this cell in this column is displayed when a user opts to edit the data in a row of the grid view. There's probably something like a textbox already listed, which is bound to a datafield. Delete the text box, and add your radio button group, then edit the databindings for the radio button group to match up to the datafield you need.