i suggest checking ticketmaster for tickets (but you probably already have)....i checked for this weekend's game a week or two ago, and there were still some available.
as far as parking...you CAN park for free on streets in the neighborhoods near main st., and walk through the yellow lot to the stadium. i used to live there, and people did it all the time. go north on main (from 610), and take a left on broadmead...then just park on one of the intersecting streets (you will be in front of someone's house, but they probably won't care....).
don't know any other sources for tickets though....never bought from a scalper.