Deus Ex: HR is currently at £4, which is super cheap. I think that comes out at something like 200,000 USD; a good deal in any case. Seems to be a run of daily sales. Worth keeping an eye on.
http://www.greenmangaming.com/s/gb/en/pc/promo/birthday/?top
http://www.greenmangaming.com/s/gb/en/pc/promo/birthday/?top