Hey everyone, sorry for reviving a long dead thread here but it seemed to me that the information here could use some clarification.
You should talk to the school directly. They will have English speakers there. Ask them how much it costs. From my experience, 1 year will be well, well over $10K USD.
When I first read this I it was saying that tuition would be 'well, well over' 10,000$USD. Tuition for Japanese Language Schools is generally around 1,200,000yen for a 2 year course. Adding in living expenses and spending money you will go well over 10,000$USD/year. If you subtract part-time job pay from this, however, you should be able to keep it under.
Living expenses depend very much on WHERE (and obviously HOW) you live in Japan. If you live in Tokyo you will be living off cup ramen on 100,000yen a month. If you live in the country-side not only are prices cheaper, but there's not as many places to spend your money. One could potentially live quite well on 100,000yen a month. As long as your liver doesn't have a superiority complex.
It's also important to take into consideration the initial expenses involved with getting an apartment here. If you're going to be here for 2 years, signing a lease even if you have to pay reikin (thank you money to the landlord), a deposit and a guarantor fee may likely end up being much cheaper than living in a gaijin house for the whole time.
The cheapest way is to look for a school in the country side with dormitories. There are some schools like this where the dorm rent is only 10,000-20,000yen/month. Of course, there are pros and cons to dormitory life.
Some schools accept students all year long. The real wait for you will be the time it takes to process your student visa (usually called pre-college visa).
Some schools accept students all year if you're already in Japan with a visa. Most schools only accept students from abroad (getting them visas) in April and October. This is due to the bureaucracy of applying for visas. School application deadlines are usually 3-4 months (sometimes more) before you would start school.
Hope this helps someone,
-a7mouse