I've looked at the difference in the bread calorie counts and could never justify going "light" with any product. Basically, for what I ate of bread, all I would need to do is 50 jumping jacks to make up the calorie difference between regular and "light" breads. Besides the calorie differences, I've found the ingredients used in most "light" products are actually worse for you than the regular ones (more chemical replacements to allow the calorie count to be lower and still "taste" good).
My solution to both the calorie count and price was to start making my own bread. For the price of the ingredients to make bread (which is less than store bread uses), I can get 3-4 homemade loaves to the 1 store loaf (need to average this over about 30 homemade as there is an up front purchase of some ingredients, but they'll last nearly a year worth of baking).
The advantage to sticking to the philosophy of only eating bread you make is (1) you burn calories making the bread, assuming hand kneading vs using a machine, (2) I ate less bread because it was so good and more nutritious than the store bread, I was more satisfied and thus craved it less [similar to why you don't eat a whole bunch of banana in one sitting], (3) was less expensive.
Also, when I ran out of time or didn't feel like baking, well, I just learned to go without bread or bake alternatives (like homemade biscuits).
I realized recently that I haven't baked any bread for the past 3 months (got too busy during the holidays and just haven't worked it into my schedule). And I really haven't felt like I was missing anything.
The only time I have bread is when I occasionally go out to eat, and when I have it, the bread doesn't taste nearly as good as my homemade stuff.
Something to consider as an alternative.