The first time I went to my (long-time) dentist without dental insurance, I was shocked at how much higher my bill was for routine services. I asked about a discount or any insurance/discount program they could recommend, and they didn't have any suggestions. I was disappointed by this, so I started researching online. I found a dental discount program (not insurance) that costs me about $100/year and saves me more than that, even with just routine services in a year.
I got the impression that the dental staff weren't too happy about it the next time I went. I wanted to tell them that I'd have gladly have paid them the money I was paying the discount program, if only they'd seemed willing to negotiate a bit of a discount. I guess I'm too reserved/polite/whatever so I just said nothing. But I do think it would be good business for a medical office to offer at least a small discount to a long-time patient without insurance.