Ok, we've nearly got Astrosmash, then, because I did some experimenting last night/
There are four rewards:
T-Shirt: 7500 points, any difficulty
Poster: 50,000 points
Mobile: 10,000 points, Hard dificulty
Getting the mobile is easier than you think, because once you move up a few levels, all of the enemy ships more than make up for points lost to rocks hitting the ground.
Shark Shark also has four rewards:
T-Shirt: ???? (I beleive it's 5,000 points or Level 3)
The Mobiles are not mentioned in the description for the Console versions of the game, only the upright and cocktail table cabinets. I'm assuming they're there, but someone should verify that.
I've got 5 of the 8 rewards.
On Astrosmash I got the T-shirt, Poster, and Mobile. I have been to 90,000 (hard) and 200,000 (medium) but have not gotten the Gold Trophy.
On Shark Shark! I have the T-shirt, and Mobile. I have been to level 6 (easy) and level 5 (hard) but have not received either the Poster or the Gold Trophy.
The Shark! Shark! poster was at level 7 on hard (was at about 19,225 pts).
So I am only missing the Shark! Shark! gold trophy now. Sounds like that will be at level 9 or 10.