It doesn't matter if you purchased the property or the right to use it. Either way it is a product you purchased and therefore it is your right to sell it. Valve, I honestly never saw the enjoyment in your games anyway, I find them gimmick-y (mind you, that's just my opinion, I know for a fact they must be good because of how popular they are) but the fact that you're company is so downright arrogant and pigheaded shows you and your staff has the mentality of a 4 year old with a temper tantrum. I still, clear as day, remember your staff calling the PS3 a "developer's nightmare" all because you were too lazy to figure it out. I don't even like the PS3 and even I have to say, grow up.
Honestly, fall into oblivion with the rest of those crack game dev companies, you won't be missed by me, that's for sure.
BTW, I purchased all games from Valve used. Gotta love EBGames