Although cheops pyramid had a gold crown in the past but not the highest value cos gold available near giza so transferring cost small
The smallest one covered and established not only by limestone but also by granite
And granite was available only in Aswan ( my live and birth town ) south Egypt far nearly 1000 km also the granite is very limited so the cost of transferring very high
So the established value was more expensive
Why they are different in size
Khufu is the grandpa's of Menkaure and the son of khufu is khafre
Khafre can not establish pyramid bigger than his father cos after khufu death khufu claimed as a god
And if khafre made pyramid bigger people will not respect him and my make revolution against
The same for Menkaure his father after death claimed as a god
But he was intelligent to make a glorious pyramid he established smaller but with a valuable one