python: for practice and trianing case purchase cart

commodity_list=[('bicycle',9000),('iphone',20000),('tesla',20000),('python book',109),('mac book',2000)]

deposit=input('please input your budget:')

 if deposit.isdigit():

    deposit=int(deposit)

    purchase_item=[]

    while True:

       for i,v in enumerate(commodity_list,1):

           print(i,'----',v)

           choice=input('input your choice Commodity No【Quite:q]')

            if choice.isdigit():

              choice=int(choice)

              p_item=commodity_list[choice]

              if deposit>p_item[1]:

                print('your choice is %s,your balance is %s'%p_item,deposit)

                purchase_item.append(p_item)

                deposit-=p_item[1]

           elif  choice=='q':

             print('------your list---------')

               for i in purchase_item:

                    print(i)

                    print('your balance is %s',%deposit)

                      break

          else:

            print('please input right Commodity No')

else:

   print('invalid string literal')