Is canned soup worth the convenience? Some split pea soup questions.

I just had a can of Progresso split pea soup for dinner, and it was tasty. I looked up recipes for split pea soup, and many of them had ham bone as an ingredient. I'd like to watch my calories. How might I estimate the caloric contribution of something like that?

The can of soup (two cups) was $3. A lb of split peas is $1. I'm sure even with other ingredients, the homemade soup can cost several times less than the can. But I can heat up the canned soup in a microwave (or stovetop) and be good to go in minutes. Hmmm

Also, if I were to make my own split pea soup, I was thinking of tossing in some frozen mixed vegetables (corn, string bean, carrot). If it's a 2-hour simmer, when should I add that in?

As a side benefit, cooking the soup on my own would avoid a small amount of nitrites that comes with the ham/bacon in the Progresso soup.