Last year, non-balcony seats under $15 were not hard to find. Sure, it wasn't every game. But we went to several games last year and I never paid more than $15/ea through Stubhub.
This year, I just can't find the same deals out there. It was posted here recently that the team attendance is highest since 06 (07?). I think ticket sellers are catching on to the higher demand. It sure seems like I'm paying more this year. I suppose its a good thing though!