The International 7 main event will take place August 7th-12th.
Ticket prices have gone up from last year, with "Midweek" (August 7-10) tickets costing $100 and "Finals" (August 11-12) tickets costing $200. Tickets go on sale in just about a week, April 4th in two waves - 10am and 10pm PST, once again via Ticketmaster.
Tickets have sold out extremely quickly in past years, so it is always advisable to prepare in advance if you hope to snag one of the cherished few tickets to KeyArena in Seattle.
Further details are available on Valve's International 2017 Ticketing FAQ.