Plumbing company charges $230 per sink basket

I had a tenant in one of our units in San Antonio mention a leak under the sink, so I called a plumbing company to go take a look. The plumber gets there and calls me. He says no big deal, the sink strainer basket is leaking on the left side. It needs to be pulled and new gasket added and putty, and put back together. So ok, I tell him. The charge is going to be $230 to replace, which is high for other markets I'm in, but I'm ok with it since he is already there, and I tell him to go ahead and replace it. But I ask him, how about replacing the right side basket as well, since they were installed at the same time and you are already there. He tells me to replace the second basket he would charge ANOTHER $230, so $460 for a weekday truck roll and fifteen minutes of plumbing. To me, plumbers should be charging an hourly rate, plus materials. Obviously this company is on a different wavelength, so they won't get my business again.

Does this make any sense?