Yes, I do find them worth it!
A. I buy meat and poultry in bulk and then break the packages down into meal-size portions before freezing.
B. The bags are more effective at preventing icing and freezer burn than ordinary freezer bags or plastic wrap.
C. I'm less likely to order out or run to the store and pay non-sale prices for meat because I have a variety of meats at the ready in my freezer.
D. I vacuum-seal and freezer leftovers in individual portions. It prevents waste and helps me to avoid dining out on nights when I don't have time to cook.
I buy the Foodsaver rolls instead of bags so that I can customize the size of the bag. I order them directly from the Foodsaver website when they have a good coupon and I get enough rolls to last me until the next good coupon is issued. I haven't sat down to estimate the "cost per bag", but as I stated above, the cost-savings from no wasting food and taking advantage of sales more than negates the cost of the bags.