Good idea with the extension methods.
Here is one I came up with after reading this post:
public static class Extensions
public static GridViewCell GetCellByCellInfo(this RadGridView gridView, GridViewCellInfo cellInfo)
GridViewRow RowFound = gridView.ChildrenOfType<GridViewRow>().Where(w => w.Item == cellInfo.Item).FirstOrDefault();
GridViewCellBase cellFound = RowFound.Cells.Where(c => c.Column == cellInfo.Column).FirstOrDefault();
return cellFound as GridViewCell;