Ok,
Regarding the fixed shipping rate, my solution would be to set all your product's weight to 1g and then create :
- 1 shipping method with the "minimum/maximum weight" options set to 0-3
- 1 shipping method with the "minimum weight" options set to 3
Regarding your "garlic" shipping rate, my solution would be to :
- Set all your product's weight to 1Kg
- Create a shipping method with the "Price" option set to $9.50 and use the "price per product" option
However you can't for the moment directly restrict a shipping method to a product's category so if you create these shipping methods, both will or just the second will show with and extra shipping rate, because of the "price per product" option.