First off, you've just been introduced to the concept of the loss leader and the product lock. I think it may have been the original Mr. Gillette who thought of the idea of selling the razor handle and a blade or two at a loss, then selling new blades that only fit into the original handle at a massive markup. Realize that razor blades are just sharpened steel and cost a couple of cents to make and distribute in huge amounts, so even at a buck each the profit margin is huge. So if the handle costs $20 to make but they sell them to you for $10, they have to make up $10 in blade sales. Guess what - those blades, even the quadruple ones with springs and all that other vibration junk, probably cost a nickel or a dime to make. But they charge $20, because the blades only fit onto that handle and nobody else is allowed to make replacement blades due to the design patent. If the patent expires, they quit making the handles since nobody else is going to risk making handles at a loss, and market a new razor handle with a new blade design.
It's a business model that has made a lot of money for decades. There are four ways out of the cycle... First, you can just buy cheapo handles and blades that have been on the market for many years, since the prices have dropped to a more reasonable level. Second, you can buy only bulk pack disposable razors like the pink single or double blade ones hotels will give to women who forget their blades and need to shave their legs once during a trip. Third, you can spend some money on a high quality straight razor, learn how to use it, and keep it sharp yourself. Fourth, you can buy a nice electric razor which, if you get a good one like a braun, can last you many years and only need a new foil and cutting blade every year or two depending on how tough your beard is and how clean you keep the razor.
I went with option 4 because my skin bubbles a bit when it gets wet so using a regular razor makes me look like I rubbed my face in glass. I buy only Braun razors, and they typically last me at least 4 years. I usually buy a replacement foil and cutter (about $20) every 2 years unless I drop the thing and damage the foil, but I'd probably get a better shave if I replaced it every year or more. I buy the cheaper braun razors with the single larger-radius cutter instead of the multiple smaller radius cutters, because they seem to work better on my face.
There are Braun razors that cost well over $100 (my first braun cost $130 and was a christmas present) but it lasted 6 years and was so awesome, it sold me on the brand for good. I have not been disappointed with braun razors since I started using them 19 years ago. Remmington foil electrics don't have the same quality, and the rotary electrics aren't sharp enough and start pulling hairs out by the roots after a week or two of use. The brauns just keep working as long as you're not abusive and use the little cleaning brush at least weekly to keep them clean. The cheapo one I use now is I think their model "105" if I recall correctly (or something like that), and it costs about $40-$50. That's cheap enough that instead of keeping regular blades as a backup, I bought a spare electric in case my electric dies right before I have to go to work.
As for the vibrating ones, they help on the principle that a lot of tiny cuts are more effective than making one big cut all at once. Supposedly it means that as you draw the blade across your face, the vibration is like the razor making hundreds of little tiny cuts as you make the one pass across your face. It sounds like it ought to help especially for people with tough beards or sensitive skin, but I've never tried them.
And BTW your school's economics teacher must suck if you hadn't heard about the razor blade marketing model. It should be taught in the very first high school class where basic economic principles are introduced. It is very odd that you've gotten as far as you have in school without being taught that... Damn commie teachers must be afraid that if kids learn about gillette and razor blades, they'll turn in to evil capitalists
