find the unique values of a dataframe and return in a dataframe form

I have the following data frame

df = pd.DataFrame({'fruits': ['orange', 'mango', 'apple', 'grapes', 'orange', 'mango'],
                   'price': ['40', '80', '30', '40', '30', '80']
                   })
    fruits  price
0   orange  40
1   mango   80
2   apple   30
3   grapes  40
4   orange  30

I want to find the unique values of each column and return back a dataframe

fruits  price
0   orange  40
1   mango   80
2   apple   30
3   grapes  NaN

I am doing the following

df=df.apply(lambda col: col.unique())
df=pd.DataFrame(df).transpose() 

which returns the following that is not what I want

            fruits                      price
0   [orange, mango, apple, grapes]  [40, 80, 30]

Any ideas?

>Solution :

You can apply pd.Series.drop_duplicates

out = df.apply(pd.Series.drop_duplicates)
   fruits price
0  orange    40
1   mango    80
2   apple    30
3  grapes   NaN