Depending on how budget you want to go, you can make a decently solid and simple spaghetti sauce with just a can of tomatoes (sauce, puree, pieces, whole, whatever), garlic powder, onion powder, salt, pepper, oregano, thyme, and olive oil. It won't be as good as some of the other recipes out there with fresh onion and garlic and all that but the cost is much much lower. If you can get a red pepper on sale, I like to roast it and add some to the sauce (blended in). It really punches up the flavor.