Without a workbook, the best I can do is respond with a verbal description.

What I would do is create a pivot table on the data where the row header is the product. This pivot table gives you a unique list of product names. You an use this list to populate the ComboBox for product selection.

In the same pivot table, in the values area put the value you are looking for and instead of SUM, use MIN.

When the product is selected, find it in the range of the row headers in the pivot table, offset one cell to the right and grab the minimum value associated with it.