I got decent tickets last summer through the Yankees website, which I suppose just connects you to the ticketmaster site. Yes, the seats were "high up"; but the view was excellent and we were directly above the Yankees dugout. Even these "High level" tickets cost at least $30 each....but we (myself, friend and 2 children) thoroughly enjoyed the game. You may get lucky (depending on number of tickets together) and find something lower level (at a much higher price). I began looking in June....for a July mid week game.
You can always check Ebay, as well...but those tickets always end up costing big $$.
DEB