Well I don't know which systems you have so some of these might not be for you, but I can recommend all of the following for the price:

Red Steel 2 - See my post earlier.

The Beatles Rock Band/Lego Rock Band - Reasons should be obvious enough, as long as you have instruments already.

DJ Hero 2 - I had a great time with this, though again it requires a peripheral most wouldn't have without the game.

Prince of Persia: The Forgotten Sands - If you enjoyed The Sands of Time trilogy, you'll probably like this. It isn't as good and a little too formulaic, but for the price it scratches that PoP itch that few other games can.
Singularity - Similar to TFS it is in no way revolutionary, but an enjoyable old school shooter with some interesting ideas that doesn't completely live up to it's potential, but is worth a run through if you enjoy games such as Bioshock or more traditional FPS.

Enslaved - While I didn't enjoy it quite as much as I expected, the characters are what make the game, and it's likely to appeal to anyone who can accept less than stellar gameplay for the sake of the story. Also it has Andy Serkis, who's always awesome!

The Conduit - The story is garbage and it isn't the most original shooter, but I still had a great time mostly because of how fun the Wii Remote can be for shooters when utilized correctly. It's a short but sweet shooter that doesn't take itself too seriously (most of the time), and can be a lot of fun if you enjoy the genre.
Unfortunately those are all I've played (and would recommend), out of the $9.99 and below group. A few I haven't played but are probably worth the price would be Killzone 2, Alpha Protocol, and Bad Company 2 (as well as others I'm forgetting).