This stamp is used for official documents. Getting a bank account, buying a house, etc... Usually big stuff. For most foreigners, they will probably only use it once. Which is a bit sad because the concept is so awesome.
A hanko can hold only a few characters in it but luckily it could fit my name. Now since I don't have a Japanese name, like many foreigners; I could get away with whatever I want. I went with a rough translation of my name in hiragana, which is one of the Japanese alphabets.
I didn't translate it but one of the coordinators helping my with my job did, which was kind of her. She also helped out a bunch of other lost gaijin.
As far as price range goes on a Hanko, it will range anywhere from $4 (which was how much this one cost) to easily over $100 or maybe more. This all depends on the size and material of the hanko, which could be something like ivory, bone, or a rare wood. Cases can be just as expensive, when I was in a department store, I saw some cases selling for over $4,000.
Why would someone buy something so expensive? I like to juxtapose it with the scene from 'American Psycho' where Christian Bale is envious of other rich business men and the fancy paper their business cards were printed on. Its all about class. Which, I do wanna be classy but I'm also super cheap and my dog carrying case will get my by just fine in Japan.