I think no one in the world doesn’t like to spend money when he/she can do it for free.
In a trip, one of your costs is the entrance fee for tourist attractions. for example, in Iran, you will charge 5 to 20 dollar for visit an area or museum. it’s not an expensive cost, but when you can visit up to 20 places in a historical city and you have up to 6 historical cities with this feature on your trip, this going to be a big amount.
But there is a way to a reduction in costs. this is a simple way and you need just to arrange your trip in an exact date.
The 19th of May in every year is the International Museum and Cultural Heritage Day.
In Iran on this date, all museum and tourist attraction is free of charge. As you may know, this is the best time for visiting Iran.
Very nice weather and some seasonal festivals such as Rose Watering (Golab Giri) in Kashan make the May is the best time to visit Iran.
My suggestion is to visit Isfahan, Shiraz or Tehran on this date. This is because these cities have several museums with a special thing to see and a bit expensive entrance fee.
For example, if you are in Tehran on this date, you have enough time to visit National Jewelry Museum, National Museum, and Carpet Museum.
Or in Shiraz, you can visit Persepolis UNESCO Site, Pasargad UNESCO Site, and Naqshe Rajab area.