From my rice cooker hero Roger Ebert, i got the idea of ADDING things to canned soup. It's a good idea: adding less processed food minimizes the oversalted CANNED taste.
I found two ideas for canned clam chowder in some cookbooks. White clam chowder is what you want; I used the Progresso brand. I would link to it on Amazon so you could see the can, but Amazon sells it for such a ridiculously high price! This soup is often on sale for a dollar or a little more: keep your eye out at your grocery store or even at your CVS or Walgreens.
Andrew Schloss, author of Almost from Scratch, suggests the addition of canned white beans plus red pepper flakes and garlic. Almost from Scratch: 600 Recipes for the New Convenience Cuisine
Pretty good! And white beans are healthy. Don't forget to drain the can. i can't remember if Schloss said to use the liquid, but I always drain canned beans. I added some additional milk too.
Then I decided to add to Schloss by way of the famous San Francisco foodie Nancy Silverton.
I didn't do exactly what Silverton said (add garlic, shallot, and 40 snipped chives--yeah, right). I did add what I had around: some spinach, some corn, and more milk. I didn't follow her measurements either.
This can be heated in the rice cooker, of course. But, lacking that, you can mix all the ingredients in a big bowl and heat in the microwave.
One last thing: Silverton wants you to add bacon. I heated up a piece in the microwave. It did add some flavor, but would not be essential.
This took no time at all, ended up including veggies, and is cheap, cheap, cheap.