I d go with
Create A DataTable
for each rows as Datarow in Gridview1.Datarow
Dim cValue as String=ctype(rows,"LabelorTextbox",textbox).text \\you are getting the cell value here
\\insert the value to your created Datatable here
Next
combobox.datasource=your created datatable
combobox.displaymember=your datatable column name or id
combobox.valuemember=your datatable value column name or id
combobox.databind
This code has not been tested but the logic tested in my own applications million times ;) i hope it helps you.