What Microscopes should I get?

Ok so I am Absolutely clueless when it comes to what Microscope I should buy so maybe you can help me. I am in college and going ito forensic science. I want a good microscope not a cheap toy one, I Want a real one,lol. But I want one that I can View hair, fibers, saliva, cells, Bacteria, Maybe parasites. Is there a micro scope that I can View all thees thing? Also what is the highest magnification a lens can have? is there a microscope with more than 4 lens?