<asp:Repeater runat="server" ID="cataloguesRepeater">
    <FooterTemplate>
    <table>

     <tbody>
       <tr>
         <td>
              <asp:DropDownList runat="server" ID="dropDownList1" />
         </td>
       </tr>
     </tbody>
    </table>
    </div>
    </FooterTemplate>
</asp:Repeater>

private void CatalogueItemCommand(object sender, RepeaterCommandEventArgs e)
{
  DropDownList dd1 =(DropDownList)e.Item.FindControl("dropDownList1");
}

protected void Page_Load(object sender, EventArgs e)
    {
        cataloguesRepeater.ItemCreated += cataloguesRepeater_ItemCreated;
        cataloguesRepeater.DataSource =  new [] { new { title = "item1"}, new { title = "item2" } };
        cataloguesRepeater.DataBind();
    }

    void cataloguesRepeater_ItemCreated(object sender, RepeaterItemEventArgs e)
    {
       if (e.Item.ItemType == ListItemType.Footer)
       {
           var ddl = e.Item.FindControl("dropDownList1");
       }
    }