Cento versus Rao marinara sauce
I know Rao's is supposed to be a great restaurant, but I spent over $7.00 a bottle on the Basil marinara and HATED the sauce. Way too heavy a hand with the herbs. I didn't think you could put too much basil into anything until I had to eat two jars of this stuff. I would look for Barilla, if you can find it. A little less expensive. But, try the Cento and see if you like it. Try the Raos, although it IS the one of the most expensive. Try a few before stocking up. Everyone has different tastes. You may find yourself adding a little garlic powder or basil or nothing at all, if you like it. I was surprised that I didn't like the Rao's, and there was nothing I could do to a sauce that had too much basil to improve its flavor except dilute it with unseasoned tomato sauce. I also have had good luck with Newman's and Central Market's house brand (they are an HEB), in a pinch. It may be that I prefer blander sauce that I can season a bit myself, so -- like I said, try a few before stocking up. You can manage some dried garlic and basil in your dorm -- not hard to stir in.
Rao's is an A+ in jfood's book and he waits for a local store to sell two 32oz bottles for $10. He always has a few bottles in the pantry. He would rate Centos a solid B/B+. Not as good as Rao's but a nice alternative. The other two that jfood uses are Patsy's and Lidia's.
I tried Rao's marinara for the first time last night. It's probably the best ready-made marinara I've ever had, although it is expensive ($8 locally). I concur with the advice to wait for a sale and then stock up.
There are many affordable *good* to *very good* marinaras (marinari?) out there, though. In New York state, for instance, there's "Casa Visco", which is quite worthy. I remember "Real Torino" brand as inexpensive but good, although I haven't had it in a while. (Apparently, it's now called simply "Torino").
Really, the key is to check the ingredients: if it contains good ingredients, it's probably good. If it contains crap, it's probably... well, crap ;)