TheThoughtlessOne
CAGiversary!
Family Video has Sleeping Dogs used for $19.99 with $1.99 shipping. I don't have much experience with them, but this is about $10 cheaper than any other site.
http://www.familyvideo.com/catalog/product_used.php?products_id=-400445
http://www.familyvideo.com/catalog/product_used.php?products_id=-400445