This is true only about the actual beer ingredients. The truth, however, is that becomming an all-grain brewer is much more expensive than being an extract brewer. I brewed extract kits for a long time with about $140 worth of equipment. In the last year, I have spent upwards of $800 and counting on all-grain equipment. Thinking about it that way, it would take a whole lot of all-grain batches to bring down the overall cost-per-batch to what is was when things were canned and simple.
So I'm going to make the comment that, all things considered:
Extract=Cheap hobby
AG=Expensive hobby
The fact that I'm saving $6 in ingredients per 5 gallons to do all-grain is offset by hundreds of dollars spend on boil kettles, insulated mashtuns, tanks, testing equipment, books, etc. etc. etc. IMHO, if you want this hobby to not cost you a ton stick with the cans!!