At 1/3 you'll insult the person every time. What really makes me nuts is that when I have machines available, they're fully serviced and being sold for less than the going rate for a service, and I mention that in the ad. They still pull that.
If a person started at 2/3 I'd still say no because of how I price, but at 33cents on the dollar, I want to use all those words I've been told not to use in polite company.
I do negotiate on machines I Want that are priced too high. The Frister and Rossmann for instance. I set a price I was willing to pay and made an offer. That said, I started at 80% of asking price. And I showed up to ask. If I'd started at 33%, as far as I'm concerned, she'd have been totally in the right to throw my rear end out on her porch.