I can't believe how cheap these are. It costs about $4 for each Gilette Fusion cartridge, yet for $13, you get enough to DE blades to last you about 2 years, if you use 2 blades a week. I guess that doesn't factor in the increased cost of the razor handle or shipping. If your razor handle costs $60, because they can be expensive and you buy only one, uh huh, and it lasts 5 years, then that is about $12 per year. Then, $10 for shipping for both. Say $25 for both, per year for DE shaving.
If you need two Fusion cartridges every week, that would be 100 per year. At $4, that is $400 per year on cartridges. So, about 16 times as expensive, at full price. But, I'm getting my 100 blades on the Black Friday special for $6, instead of $13, so I'm saving a little more than that.
Oh, I've used them before and I know they work. It's ironic that the kind of people who get involved in this hobby are usually well to do, when the hobby would benefit the poor much more than the rich!