1. If you have any desire to make pasta sauce from scratch, try it! It doesn't need to be cooked for hours or anything. In fact, straight-up tomato sauce from a can (the plain kind that is called "tomato sauce") is almost fine all by itself. If you have fresh basil available, add that, but if not, put in some italian seasoning and a bit of olive oil and let it simmer for a few minutes (10 or 15). If you're not too picky, this is a fine and extremely cheap sauce for pasta. (However, I usually do use sauce from a jar. If you're watching your weight, look for a sauce that is 70 calories or less per serving.)
2. You can reduce the calorie content (relative to volume) and make pasta more nutritious if you add vegetables. They provide a lot of volume and experience for not many calories. The ones I most like to add are onions, mushrooms, spinach, arugula, and zucchini. If you add a leafy vegetable like spinach or arugula, throw it in at the end so it doesn't get too cooked (unless you like it that way).
3. Garbanzo beans (also called chickpeas) are great in pasta sauce, especially instead of meat. Here in Denver, they're about 90c a can for organic, or 50c a can for regular, and a can is about 3 servings of 1/2 cup each, which is plenty for a serving of pasta. Beans are healthier, cheaper, and easier than meat - what's not to like? Some people like canneloni (white kidney beans) in pasta too.
4. Wal-Mart now sells whole wheat pasta in boxes for $1/lb, which is an excellent price. The product (I buy the whole wheat fusilli, which is the spiral one) is indistinguishable from the $3/lb boxes found at health food stores. If you eat a lot of pasta, it is worth visiting a Wal-Mart Supercenter occasionally for this alone (though they also have cheap canned beans, including organic, and all kinds of other cheap things).