Two references to Ain't No Sunshine and nothing about Heartattack and Vine?

Boney's high on china white, Shorty found a punk
Don't you know there ain't no devil? There's just God when he's drunk
Well this stuff will probably kill you, let's do another line
What you say you meet me down on Heartattack and Vine

As far as buying the Black Box, you should only need to pay $40. HL Ep1 did not require HalfLife 2 to play, and I can only assume Ep2 will follow suit. Also, you can purchase individual games online though Source (Counter-Strike, Day of Defeat), so I wouldn't see why it would be any different for Team Fortress 2.