We make a huge salad every 3 days or so (me and my husband eat so much of it!) and it's much cheaper than buying the premade ones. We change it up with whatever veggies are on sale so it keeps it new and exciting (as much as a salad can be exciting!).
We do a lot of roasted vegetables, it's so easy. A little bit of Pam, some seasoning and the oven does all the work.
For easier nights when we are in a hurry (and to avoid going off our diet plan), we use the frozen steamed bags. There are a good variety of them in the store and they average about $1 a bag for 4 servings (we both do 2 cups of vegetables plus salad at dinner).
I think for us, it was more of getting into a routine. Now I find it easier and more satisfying to do what we are doing instead of relying on "bad" food.