Jenyne~ I use jar sauce, Classico is low in sugar & carbs. You can also use Hunts in the can and doctor it up with spices. For the chili I use the hunts sauce, some salsa, meat, beans & spices like chili powder, cummin, cayanne pepper, salt & pepper, onion & garlic powder. Use what ever you like. I am not much of a cook so I tend to use as much pre made stuff as possible...just read the labels.
Edited to add: I think Newmans own is low in sugar & carbs also. not sure if you can find those in your area but thats what I use.