I've seen a couple of threads discussing this before, but it seems that Gizmodo have done all the hard work..
Its surprisingly close.
Source: http://i.gizmodo.com/5211540/the-true-cost-of-console-ownership-in-2009
Playstation 3
Cost of console: $400 (80GB)
Cost of 3 extra controllers: $43 x 3 = $129
Cost of charging station: $25
Cost of 2 games: $120
Cost of HDMI cable: $3
Total: $677
Wii
Cost of console: $250
Cost of 3 extra controllers: $36 x 3 = $108
Cost of 3 Nunchuks: $18 x 3 = $54
Cost of 4 Wii Motion Pluses: $20 x 4 = $80
Cost of charging station w/ 4 rechargeable batteries: $49
Cost of 2 games: $100
SD card: $12 (8GB)
Total: $653
Xbox 360
Cost of console: $300 (60GB)
Cost of 3 extra controllers: $37 x 3 = $111
Cost of 2 rechargeable batteries: $12 x 2 = $24
Cost of recharging station w/ 2 rechargeable batteries: $30
Cost of 2 games: $120
Cost of Xbox Live membership: $43 (13 months)
Total: $628
Its surprisingly close.
Source: http://i.gizmodo.com/5211540/the-true-cost-of-console-ownership-in-2009