Sleeping dog's is now on the 3rd sale since it came out. 1 Holiday, Halloween and now this one. All 3 of them it was marked down to $4.99 so I doubt it will get any lower. Except for Nightmare in North Point DLC that was 85% off on Halloween.
If you holding off because of limited funds and rather pick up on Xmas sale you can, but I doubt you will get it any better. Its a Good game and well worth the $5, esp if you liked games like Saints row, Mafia, LA Noire and GTA.
Outlast was 75% off on Halloween, so I guess you missed that one. Might be worth it to wait for a flash or Xmas sale on that one, or even check GMG and GG esp when they have extra off coupon codes.
Example: http://www.gamersgate.com/DD-OUT/outlast + last coupon on http://coupons.answers.com/gamersgate-coupons (Code G2PO) gives you an extra 5% off


