Next time you're at the grocery store, stock up on some of the cheapest tomato sauce, tomato paste, and whole or diced tomatoes that you can find. Don't worry about the brand; we're going to use the great equalizer and make them into a good product for cooking....table sugar.
If your tomatoes are bitter or sour, try sweetening them up with a teaspoon of sugar. This will generally work to make your recipe tastier and really levels the playing ground on whether or not you use the expensive product or not.
Actually, the sugar works great on ANY canned vegetable. Try adding a teaspoon of sugar, and a tiny bit of minced or grated onion to your next can of peas, corn, carrots or whatever. It makes a huge difference in the flavor. Plus, it allows you to buy more by price, choosing canned or frozen according to your budget, rather than worrying as much about taste.
(I buy the Kroger Value canned vegetables and the off brands at Grocery Outlet, and with this treatment, nobody ever complains at dinner)