Tickets for Boca Jr vs. Gimnasia La Plata

I'm an American college student living in Buenos Aires for two months, and one of the things I really want to do before leaving is attend a Boca Jr. match. The game I would love to see is on the 21 of June against Gimnasia La Plata. Can anyone offer advice on how I would get tickets for the game, or perhaps be willing to sell me some tickets directly?
Thanks!