First, thank you everyone for all the replies. The direction this thread has taken seems to be towards performance. While I enjoy it , for my future vehicle this is not my main concern. I will be doing a lot of commuting with this car so I have to be conscious of gas mileage. So even though my list is full of cars that are a bit sporty you get the idea.
The is350 would be a perfect medium between gas, luxury, and performance but unfortunately I just cant get one for the right price under my circumstances. But overall like I stated in my opening post I am very determined to keep my payment under $400.00 a month. Seeing as how I am a full time student, I can not work as much as I used too. Which is why the is250 F-sport to me seems like the next best thing.
It seems a lot of former g35/37 drivers have nothing but good things to say about their cars which makes me happy to hear. My search is still continuing for the right car. I've expanded my search to 370z's as well . So far I've found quite a few in my price range and I have grown to like this car much more then I previously did.