Don't really know a lot about the Argo Navis but lots of people here swear by them. Looking at $1000-1200 i believe.
Other option is the EQ6 which can be had for around $1800. This is the way i went as it will give you more options down the track especially with imaging and Goto is really makes things easy once set up. Definitely enjoy thrill of looking for DSO's but i'd rather spend more time at the eyepiece than finding them and then having to move the mount every few minutes to centre images.