Is $300 about right for a visit to the minor emergency clinic for a strep test?

I received a bill from those wonderful people at the doc-in-the-box I had to see the day before Christmas, and I'm a little stressed about it. Since I can't start making phone calls until Monday, I'd just like to see what others have to say....

At the time service was provided, we were informed the bill was $162. When I commented, "Wow...that's kinda high," the receptionist asked if I had insurance. I explained I did, although I didn't believe they accepted it (turns out they did,) so she revised the bill....and I owed nothing.

Two months later I get a statement from insurance and the clinic stating that the services provided actually cost $310 (an office visit for new patient...as I was out of town, and a strep test.) Of course, insurance isn't going to cover all of that, so I'm now stuck paying just as much as I would have paid if I had no insurance. I'm a little confused...did I miss something? Or is this how people in the medical field operate?

I should add...they neglected to give me a detailed receipt when I was leaving. I know...I should have said something, but I was a little out of it from being so ill.

with insurance rapid strep tests are 20$, (if possible write what insurance you have and i can find otu the price)