Car shopping???? and auto insurance?

[xoxogoodietwoshoesxoxo]

I am planning to buy a car before school starts again..
I was shopping on craigslist.com and some cars are cheap and sound too good to be true. like this one:
http://philadelphia.craigslist.org/car/741877685.html

but should i go for it anyway??
should i hire a mechanic to check the car out?
if so where can i find one and how much would one cost?
will my insurance be expensive?, (im under 18)