You can do this with programming. There's an example he

http://www.contextures.com/excelfiles.html

Under Data Validation, look for Dependent Cell Examples

JK (New England Coffee) wrote:
DATA:

A1 A2 (these three colums combined in one column)
765100 SWISS MISS CIDER MIX CS $28.50
765100 SWISS MISS CIDER MIX CS $30.00
054020 SYRUP CUPS MAPLE 100-1 OZ. CS $13.30

Both A1 and A2 are pull-down menus.
If user pulls down menu and selects A1, then A2 is returned to the right of
it.
If user pulls down menu and selects A2, then A1 is returned to the left of it.

Any ideas?