I get these ones from Morrison's:
Salad Cream, 1 level tbsp 2½
Salad Cream, Light, 1 level tbsp 1½
Salad Cream, Extra Light, 1 level tbsp 1
Cant see a Value one but it'll be 1 syn per 20 calories as no free food. (take the calories per 100g, multiply by 0.15 and divide the result by 20)