I think you ought to sell the 120mm and the extra body. That will get the most cash for the least loss of utility. The extension tube and the 2x extender wont bring anything in comparison to their usefulness, you need at least one body and the other three lenses are basic kit for a Hasselblad. If you still have to sell something, then, sell the 150 and, after that, the 50mm. That would leave you with a body, a normal lens that can be doubled to 160 and the extension tube that can be used for macro.
Frankly, at your age and in your position, you need to be worrying about other things than this kit. If I were you, I would sell it all and concentrate on doing whatever it is that you have to do to complete your studies. As it is, the kit is an expensive distraction that you cannot afford. If you really want to learn about film, about the basics, you can do that with a 35mm camera and a meter that will read incident and reflected light and has a spot metering attachment. You get a lot more practice with 36 frames to a roll for the same amount of processing time and money that you only get 12 frames for with the 120 roll in the Hasselblad and the same economy of scale applies to everything else that you might need to learn about film and how to use it when using a 35mm vs. a 6x6 camera.
So, yes, you will not get anywhere near what it will take to replace the Hasselblad and it is a lousy time to sell it, but that is not what is important to you at this time in your life. Concentrate on doing what you have to in order to get yourself to where you can do what you want in life and the cost replacing the Hasselblad will not be a problem. If you need a film camera, sell the Hasselblad kit, get a small, manual 35mm SLR with a fast, normal, lens (a 50mm f1.4, for example) and something like a Minolta IV F light meter with a 5 degree spot attachment. Get the best lens you can and stay away from programmed, automated anything. An electronic shutter that is infinitely variable within its range would be a good thing, but not a requirement.
Basically, you need a body with an accurate shutter, a good lens that is as fast as you can afford and a meter. On KEH, today, you can buy a Minolta X-700 with a 50mm f1.4 lens, both in excellent condition, for $200, shipped. Watch for a Minolta IV F with a 5 degree spot meter on eBay, but it is not necessary. May not be everyones dream system, but it will certainly do everything you need it for and it will do it for a lot less in film and processing costs than what you have. Figure out who and what you want to be; if school will help you get there, fine, do what your instructors require and finish it.