The GTR was Y46,200 for 24hrs hire, so depending on the exchange rate it's not too bad. There were three of us on holiday so divided by 3 mates it was certainly good value. Toll roads cost a small fortune though they are great to drive on. Rental was through Premium Rent - http://www.premium-rent.com/en/cartypes.php
I can't speak much Japanese, I understand a fair bit. Enough to get by.
I did a lot of research for places to visit just using Google, Travel Wiki, other Forums etc. There's quite a few threads on http://www.jdmstyletuning.com forums with other travel blogs and Japan holiday advice threads. If you put a lot of time into research you'll find heaps to do.