Create a calculation field with calc:
duration <= 36 ; price1 ;
duration <= 52 ; price2 ;
duration <= 66 ; price3 ;
Hmmm, since the duration field is: "created in hh:mm:ss format and is already rounded to nearest minute"
It's possible that Raybaudi's calculation may not work. What data type is this field? Time, Text, or Number?
Yes, Phil is right.
If the duration field is a Time field:
m = Div ( duration ; 60 ) ;
m <= 36 ; price1 ;
m <= 52 ; price2 ;
m <= 66 ; price3 ;