Tickets are available for direct purchase through the website of the organiser:
https://tickets.expo2017astana.com/en
Ticekt prices:
Open date ticket for weekend* - 8.000 KZT (approx. 20 EUR).
Open date ticket for weekday* - 4.000 KZT (approx. 10 EUR).
Fixed date ticket (for an ordinary day of the Exposition) - 4.000 - 6.000 KZT (10 - 15 EUR).
* Please note that you should exchange your ticket till 23:59 of the day before your visiting day.