Why not buy fresh low syned ones and then freeze? I always but Tesco lighter choices cumberlands at 0.5 syns each and freeze them in 2's so I get 4 portions out of the pack.
Linda McCartney are delicious - 2 syns each. Swerve that Quorn muck!
Tesco sausages have a decent shelf life of about 10 days. Freeze half a pack in batches of 2 and eat half a pack. Defrost the night before when you begin to run out.