$1200 is an outrage, it's a 6 hour job if he drinks a lot of coffee. And the parts are about $150 for everything. Timing belt alone is $30. See here:
http://cgi.ebay.com/ebaymotors/DODGE...spagenameZWD1V
http://www.autozone.com/servlet/UiBr...%7ETiming+Belt
Any good mechanic should stand behind their work. I would expect a timing belt job like this to be about $500 at the most. I was quoted $450 for my Nissan the last time I asked.
Also, another consideration is that the 3.0L engine is non interference, which means when the timing belt brakes, it does not hurt the motor. Replacing the timing belt is not so mission critical as an interference motor.
How much oil does it leak? You can buy a lot of oil for $1200.