I did a search and came up with a lot of answers, but not what I’m after.
What can I (Cheaply!) add to store bought spaghetti sauce to make it interesting?
I’ve tried hamburger, garlic, onions and oregeno. All OK but I need a change. Any suggestions?
Lost in Spaghetti Land,
Jack
Maybe an italian sausage instead of hamburger.
Besides that, I have no idea. I avoid spaghetti sauces for the most part myself. Just don’t like them (but a little olive oil, garlic and parmesan…and I’m happy)
Thanks Lsura, I’ll try the sausge.
For me it’s either Ramen or spaghetti. Or (Ugh) rice. 
Basil, and the most important, secret ingredient? Sugar or honey. It takes the edge off the acidity from the tomato and onion.
I’ve added grated zucchini and carrot and chopped green or red bell peppers. I’d add extra basil too…
GT
try bacon!!! Just make sure you cook it enough. 
Mushrooms, if you like them. You can use canned ones or get some fresh ones and sauté them in butter or olive oil (much better). Add a splash of red wine. Artichoke hearts (can also buy them canned), if you’re feeling exotic.
Tiny shrimp (from the freezer aisle. A bag is a couple bucks)
Canned baby clams.
Fresh red (bell) pepper, lightly fried so it still has a bit of crunch.
Drained pineapple chunks. (better than it sounds)
Thyme, marjoram and tarragon rather than oregano.
Additives that I have tried at different times, with their results (Caution: I don’t use storebought sauce):
Summer Sausage, chopped fine (yum!)
Vegemite (intensifies the beefy flavor, but remember to reduce the table salt in the recipe!)
Fish sauce (this didn’t work too good, I don’t recommend it)
Ground pork (a nice change)
Ground Turkey (also nice)
Ground ostrich or emu (very good if the meat is high quality)
Lemon juice (always a winner)
Chipotle peppers (turns it into a yummy mexican putanesca sauce!)
Worchestershire sauce (it was ok)
Fresh herbs (parsley, basil, oregano, marjoram, really boosts the flavor)
Fresh bay leaves (great, but you have to simmer it for a while)
MSG (kicks ass!!)
Liquid Hickory smoke (OK, that was a mistake, I admit it)
Exotic Lemon Grass Soup boullion cube (OK, look, I thought it was a beef boullion cube. It was rather compellling in its own way. The dog liked it too!)
Basil is made for bringing out the flavor of a tomato. I usually add, in no particular combination at a time: Italian sausage, oregano, basil, garlic, mushrooms, roasted red peppers, garlic, chopped Italian peppers, various hot sauces, garlic, onions, ground moose, garlic, red wine, garlic. 
Clean out the center of a large green bell pepper and a small red one and cut into long thin peices.
Chop up a medium size onion and add both to a large frying pan with a lid.
Take 2 Italian sausages and strip out of the skin and crumple it into the pan (I use Mild)
Put a pat of real butter into the pan, cover and sautee on med-low heat 15-20 mins. Don’t over-cook. They should still be a little crunchy.
Open two large jars of Prego or whatever and put in a seperate pot and heat on low while the vegs sautee. Cut the remaining Italian sausage from pack into aprox. 2" sections and add to sauce.
Drain excess liquid from veggies w/sausage and add to the pot of sauce.
Cook for and hour +/- and put pot into a sink with cook water (as much as possible without going over top of pot) to cool the sauce. When cool, reheat on stovetop (cooling and reheating takes the acidity out).
Take a ladle and refill one jar for the freezer leaving an inch or so for expansion when frozen so jar won’t break.
It’ll take maybe and hour and you’ll have a spare jar for unexpected guests.
Let me know if you try it this way and what you think.
Smoke and tomato are not mortal enemies. You could probably turn storebought spaghetti sauce into a passable Jambalaya with some hickory smoke, ham, chicken, onions, bell pepper, red, black and white pepper. Serve over rice.
If you are going to add basil, make sure it is fresh basil, not that dried crap. Dried basil tastes like tea leaves. Also, add fresh herbs at the end, not while it’s all simmering. Add dry herbs during cooking, but only after you reconstitute them in some warm water.
Dang, that sounds like something I’d like to use. Never seen it around here though.
You could bump your sauce up a notch or two, and turn in into a Puttanesca sauce with the addition of some capers, black olives & anchovies. If you’re brave, toss in a goodly amount of hot pepper.
Out of curiosity, why are you using storebought sauce instead of taking a day to make a whole buttload of homemade sauce and freezing the extra sauce in ziploc bags?
Daniel
This was my thought as well. You can buy a large can of crushed tomatoes (cheap!) and add all the stuff above to make sauce.
I do a nice marinara sauce with capers and calamata olives, and a tiny bit of fish sauce (easier than anchovies) along with lots of hot pepper too. Yum!
As for the Lemon Grass boullion cube, any decent asian grocery store should have it. It’s by Knorr!
I second the people who say “make your own.”
I used to date a guy who was very into doctoring up jars of marinara sauce. He’d add all sorts of stuff, and it turned out pretty good. Eventually I asked him why he didn’t just make his own - by the time he sauteed onions and cut up all the little bits of things and measured out the herbs, he was going through the same amount of work as making it from scratch. He just didn’t realize that the only thing different between scratch and doctoring up store-bought was an extra 30 minutes of cooking time or so.
Er… yeah, I see the “easier” party, but what about the part where they taste completely different?!? 
I use celery, onion, and fresh garlic. For spices, I use the traditional oregano, but also savory, marjoram, thyme, basil, fennel, white pepper, and small amounts of sage and rosemary. If you want meat, I suggest browning ground sirloin with fennel. Delicious.
I take my spaghetti sauce very seriously, and it’s the bomb.
Agree definitely on the celery. It adds a pleasing flavor and texture. Another thing you might try is varying the pasta itself. Use wheels or shells, for example. It’s also easier to eat!