Get Trials 2: SE. It's nearly free for another 12 hours or so. If there's a good deal on Machinarium you should really consider that, too.
I spent a few hundred bucks on last year's sale. Most of the games I got then I still haven't even installed, but then again, many of them were simply for the sake of good conscience - I've never paid for a Quake game in my life before, so I figured it was about time. Shame none of those Quake games work without using open source hobbyist non-official engines though. I also bought Bioshock for 5 bucks, which I've regretted ever since, since I didn't like it. I'd rather have paid another 15 for System Shock 2 despite already owning a physical copy (though from my understanding buying Bioshock is the only way to pay homage to the SS2 devs, as buying SS2 only helps EA, completely nullifying the whole "for a good conscience" idea).