function InputCombo(const ACaption, APrompt: string; const AList: TStrings): string;
 
  function GetCharSize(Canvas: TCanvas): TPoint;
  var
    I: Integer;
    Buffer: array[0..51] of Char;
  begin
    for I := 0 to 25 do Buffer[I] := Chr(I + Ord('A'));
    for I := 0 to 25 do Buffer[I + 26] := Chr(I + Ord('a'));
    GetTextExtentPoint(Canvas.Handle, Buffer, 52, TSize(Result));
    Result.X := Result.X div 52;
  end;  
 
var
  Form: TForm;
  Prompt: TLabel;
  Combo: TComboBox;
  DialogUnits: TPoint;
  ButtonTop, ButtonWidth, ButtonHeight: Integer;
begin
  Result := '';
  Form   := TForm.Create(Application);
  with Form do
    try
      Canvas.Font := Font;
      DialogUnits := GetCharSize(Canvas);
      BorderStyle := bsDialog;
      Caption     := ACaption;
      ClientWidth := MulDiv(180, DialogUnits.X, 4);
      Position    := poScreenCenter;
      Prompt      := TLabel.Create(Form);
      with Prompt do
      begin
        Parent   := Form;
        Caption  := APrompt;
        Left     := MulDiv(8, DialogUnits.X, 4);
        Top      := MulDiv(8, DialogUnits.Y, 8);
        Constraints.MaxWidth := MulDiv(164, DialogUnits.X, 4);
        WordWrap := True;
      end;
      Combo := TComboBox.Create(Form);
      with Combo do
      begin
        Parent := Form;
        Style  := csDropDownList; // Caso o item possa ser digitado, altere aqui para csDropDowns
        Items.Assign(AList);
        ItemIndex := 0;
        Left      := Prompt.Left;
        Top       := Prompt.Top + Prompt.Height + 5;
        Width     := MulDiv(164, DialogUnits.X, 4);
      end;
      ButtonTop    := Combo.Top + Combo.Height + 15;
      ButtonWidth  := MulDiv(50, DialogUnits.X, 4);
      ButtonHeight := MulDiv(14, DialogUnits.Y, 8);
      with TButton.Create(Form) do
      begin
        Parent      := Form;
        Caption     := 'OK';
        ModalResult := mrOk;
        default     := True;
        SetBounds(MulDiv(38, DialogUnits.X, 4), ButtonTop, ButtonWidth,
          ButtonHeight);
      end;
      with TButton.Create(Form) do
      begin
        Parent      := Form;
        Caption     := 'Cancelar';
        ModalResult := mrCancel;
        Cancel      := True;
        SetBounds(MulDiv(92, DialogUnits.X, 4), Combo.Top + Combo.Height + 15,
          ButtonWidth, ButtonHeight);
        Form.ClientHeight := Top + Height + 13;
      end;
      if ShowModal = mrOk then
      begin
        Result := Combo.Text;
      end;
    finally
      Form.Free;
    end;
end;

procedure Tfrmproduto_pedido.BtnImprimirClick(Sender: TObject);
var
  List: TStringList;
  vResult : String;
  indice : Integer;
begin
 
  try
    List := TStringList.Create;
    List.Add('Sem Preço');
    List.Add('Com Preço');
 
    //Rseultado string do item selecionado
    vResult := InputCombo('Seleciona o tipo de relatório', 'Descrição:', List);
 
    // Se quiser o indice selecionado por fazer o seguinte
    indice := List.IndexOf(vResult);
  finally
    List.Free;
  end;
 
  // Testando o retorno string
  if (vResult = 'Sem Preço') then
  begin
    ShowMessage('Sem Preço');
  end;
 
  if (vResult = 'Com Preço') then
  begin
    ShowMessage('Com Preço');
  end;
 
  // Testando o retorno Integer
  ShowMessage( List[ indice ]  );
end;