Top Shop, Tall: Infinity, Crossroad Crisis, Battle Hunter, and Shooter: Starfighter Sanvein are some of my favorites of the budget release PS1 games. I'm not sure if all come from the Simple 1000 series, though.
Edit: You should probably change your post title. While Agetec put out some good budget games, there were other companies and developers that put out great budget titles, not necessarily from the Simple 1000 series. (and another Japanese sort of "Simple 1000" type series... can't remember the name of it though.) If we are going to discuss PS1 budget titles we shouldn't just stick to the Simple 1000 games >_>