The closest I've come is a no sugar added ketchup I got from Whole Foods Market, a big health food chain of supermarkets. I don't remember the total carbs. It was good though, like a tasty tomato paste. Now I just use tomato puree or such on my eggs since I cannot find the sugar free ketchup any more (I should inquire at the store).

Is the low carb kethup coming out lower carb than the tomato would make it? That might be wierd. Though there are some good volume replacers out there. So those plus some tomato extract may be an okay way to get rid of some of the tomato sugars.