18K will get you a very good condition 05-06 in NY, so Jersey shouldn't be TOO much different. You can get a mechanic to look over the car, and I wouldn't even think about getting a used car without doing so. Read the post in this forum, "How to buy a used WRX or STI", lots of good things to look for.
Insurance will be high if the car is in your name, so get a couple quotes before you commit.
Good luck.
