If you have an Xbox Live Gold account you can get it here free:
http://marketplace.xbox.com/en-US/Product/Battlefield-Bad-Co-2/66acd000-77fe-1000-9115-d802454108a8?DownloadType=Game#LiveZone
I loved that game – the breakable environments were very cool, and the characters were fun and memorable. The campaign is too short, but not that short, and includes a couple of ridiculously hard sections on ‘normal’ difficulty, but still very worth it.