Des Moines, Cedar Rapids, Davenport, Sioux City

Iowa resources:

No used retail or store fixture companies in Iowa that I can find.
Here's  few resources that MIGHT help, or help an opening store in other ways:

Urbandale:
Iowa Grocery Industry (website)

Des Moines:
Storage and Design Group (website)
A google search will show no store fixture dealers in the state of Iowa, but your state is geographically located in range of some great deals.

For starters, you can find used shelving dealers north, south and east.  Minneapolis, Kansas City and Chicago will be the places too look for used retail shelving.  Make sure you include these cicties when running price quotes.

Michigan has a variety of store fixture liquidators waiting to serve you, and is waiting 300 miles from Davenport.
Try these nearby states:

Minnesota

Wisconsin

Illinois

Missouri