The company behind Machinarium is now selling their game for $5 (originally $20) on their site.  
From the site:

Everybody who downloaded our game illegally (for free) has now a chance to redeem himself and get the latest version of the game (Win+Mac+Linux) and it’s fantastic Soundtrack only for $5 (instead of $20).

We released the game DRM free which means it doesn’t include any anti-piracy protection, therefore the game doesn’t bother players with any serial codes or online authentication, but it’s also very easy to copy it. Our estimate from the feedback is that only 5-15% of Machinarium players actually paid for the game. If you decide to buy the game, you can be sure you’ll support directly the developers, not any big publisher or distributor.

Thanks for letting me know, just made my purchase. I did want this game when I first saw about it but ended up not getting it for some reason. But £3.50 for the game and the full soundtrack seemed too good to miss.

You'd be crazy to not check it out at this price. Wonderful game.

The level of piracy here is an absolute crying shame.

5-15%, that's not alot. 
These guys need my help... Developer Support-man AWAY!

Definitely worth it o:

I'd buy it if it was released on the Wii.

Actually purchased by ~10% makes me really sad. I need to buy this now.

Bought it full price back when it came out, and it's definitely worth the money.

I bought it retail-- absolutely amazing game!!

" I'd buy it if it was released on the Wii. "

Getting this now. How long is the game btw?