It doesn't matter as long as they are vegetarian and egg-free. There's only one brand I've found that is and it's probably cheap compared to real quality meat sausages, so I'll save save.
Oops cross-posted with pb, so I'll answer that one, too...
I only use tinned tomatoes and beans / legumes. And now Morissons has an organic line of tinned beans and the tomatoes I use are Morissons as well, so Save.
Flour for baking.