Joe gives her 1000 lire (about "a dollar and a half") according to Joe. So she buys shoes and gets a haircut and buys ice cream.
Rome must have GREAT prices! I'm going there. Haircut, shoes, and food for $1.50! For any Italians, apologies if I'm way off on the estimate and conversion of a lire. I'm going by what Joe said in the movie.
I just love the movie, but her expenses were indeed a bit weird. The taxi ride was 1000 lire and also the flowers were 1000 lire. Ok, sounds right to me. But a haircut, shoes and ice cream are not 1000 lire all together.
But this are just minor flaws, it doesn't affect the movie. So I don't matter.
The film's intended primary audience at that time was American- they wouldn't have had a clue what the relative value of the Italian currency was so this "minor flaw" or whatever is trivial and unimportant. When so many post-war economies were racked with hyper-inflation and currency values were all over the map trying to keep track of this stuff was ridiculous. Italian and other money was the fodder for endless joking about paying 50,000 what have you for something worth one U.S. dollar.
This same type of pointing out "flaws" in depicted money value is brought up in films like Ben-Hur - another Wyler movie- where how much a talent of gold or silver (won as a prize) was worth 2000 yrs ago vs. today. Apparently there isn't one right answer because there are so many variables involved.
MasterCard should make a commercial using Roman Holiday-I think it would go like: New Sandals=$2.00 Haircut=$8.00 Ice Cream=99 cents Having a day you'll hold in your heart for the rest of your life=Priceless!