I have spent some time in Argentina. I watched Argentina vs Brazil at the River Plate stadium and also watched Boca play.
When I went I stayed at Milhouse Hostel (
http://www.milhousehostel.com/) which I would not describe as 4/5*. But they do have 50 season tickets for both River Plate and Boca. They organise trips to the stadiums and general look after you.
Ticket prices are considerably cheaper in Argentina than in the UK ie Argentina vs Brazil was �2 a ticket. I would probably just go to the ground a couple of days before or the morning of the game and buy a ticket.
The River Plate ground is in a posh suburb of BA. The Boca stadium is in the working class suburb of La Boca. Parts of La Boca, are very touristy, and we were advised not to stray outside of these areas.
Most Argentine clubs have links to very hard core fans. These fans generate a huge amount of atmosphere in the ground, but I would not want to be too close to them!! A number of games have recently been abandonded due to crowd violence.
Another piece of advice is not to admit to being British, particulalry in a football crowd of 50,000 Argentines. They have not forgotten the war!! Another place to be careful about being British is in Ushuai, as lof the Argentine navy came from there.
I loved the country and some of the places we went to were El Calafate (to see Moreno glacier), Ushuai (worlds most southerly city), Los Penitentes (to go skiing), Salta (beautiful city), Mendoza (wine growing region), Iguaza Falls. Also go to Uruguay to Montevideo, and Colonia.