Another possibility is to buy the freshest corn you can find (pick your own would be ideal) and as soon as possible (withing less than an hour, if you can) husk it, cut the kernels from the cob, and freeze in freezer bags.  Squeeze as much air out of the bags as you can before freezing.

If deep frozen it will keep for well over a year and be just as sweet and tasty as the day you picked it.  It will be fine for eating "just so" or for making soup.  

In my opinion soup making is better saved for a cold, raw, rainy day.