I love salad! What I don't love is making salad every day. I buy the ingredients, but then I don't make the salad. As I've said before, dinner time is not the best time at my house. That is exactly why I'm so glad to read Jeremy's article at Generation X Finance, How to Prepare a Salad to Last All Week for Just a Few Dollars. I already have a salad spinner (check your base thrift store, I've seen them there a lot) and I can manage the rest of the directions without too much trouble.
Now for salad dressing. It is easy enough to buy bottled dressing, and it isn't too expensive, but I prefer the fresh stuff. Here's a link to my favorite ranch dressing recipe at AllRecipes.com. It has no preservatives and it is just as yummy with low-fat ingredients. Add some blue cheese if you like that flavor. Here are some other good dressing recipes to try: a list at Cooks Recipes, Nikibone.com's Salad Dressing Recipes, and Salad Dressing Recipes.
With a couple of heads of lettuce and extra ingredients, you should easily be able to make a weeks worth of salads for only a couple of dollars. Tasty and affordable – I love it!