what's the cheapest way to get divorced?

In one weeks time I can get divorced, my ex was the one that ended the marriage but she doesn't care about getting divorced yet. I was hoping she would, As she would be the one paying for it, but now my new girlfriend wants me to, so now I'll have to pay for it. I've heard you can get a Divorce Kit from the Post Office for $90. As far as I'm concerned it's just another blantant ripoff by lawyers to get it done, because of the legalilities.