gps navigation needed

hello i am new here and i need your help
i want to set a g ps navigation for my car .so i went for google search and found a site .
the price of the product between 300~400$
what do u think about it ?
is it worthy to buy?
the site is car audio car gps (http://www.cargpsnavi.com/chrysler-300c-car-dvd-player-with-gps-ipod_p858.html)
or if u knew some good sites
please tell me