Valve's $100 Valentine's Day gag was actually taken up by a lot of people, who figured the money was well spent since it gave them a chance to broadcast a message to the entire Team Fortress 2 community.
What resulted, then, were not actual engagements, but people making Half-Life 3 jokes for the whole world to see. Which may be what Valve expected all along, and is why the entry barrier to such power was set so high.
TF2′s $100 wedding rings are one dirty joke [PC Gamer]