I do make homemade sauces occasionally, but I usually doctor a jarred sauce. I love the flavor of a couple relatively low-calorie(point) jarred sauces, and I usually dilute them further by adding diced tomatoes or tomato juice (or V-8, especially spicy V-8) to decrease the calorie count per serving.
For example, I love the mushroom spaghetti sauces from Aldi (Reggano is the brand name). It's not only the cheapest spaghetti sauce I've ever bought, it's one of the best tasting, and fairly reasonable calorie-wise (even before doctoring). It's 99 cents for a l26 oz jar (80 calories per half cup serving). I add diced tomatoes to cut the calories per serving to 50 to 60 calories (depending on how large the can of diced tomatoes). If I use a 14 to 16 oz can of diced tomatoes the calorie count is about 60 calories (1 point) and if I use 2 cans, the calorie count the calorie count is about 50 calories (still 1 point).
I will sometimes add more garlic or garlic powder, but usually it doesn't need any more seasoning than that. Sometimes I will add diced green pepper and onion (that can lower the calorie/point count even further, but it still usually comes out to at least 45 calories per half cup - so still 1 point).