Nope, no lawsuits I am aware of. Take it to a smaller shop and get another quote. May also consider a "used" transmission. Keep in mind it is a foreign car and will almost always cost more to fix.
Most transmissions should not have issues that soon unless abused. My 1989 Oldsmobile Cutlass had 228k miles when I sold it, never had a transmission service (but I should have!).
As a side note being a "Japanese" car does not mean it is reliable. There are a lot of people out there dumping thousands in repairs on their foreign cars and still swearing they are the most reliable vehicles out there, I always have to laugh after I see people I know personally who do that, but most of the time I help them fix them anyway.