Midas Overcharged for parts on exhaust system repair. Catonsville Maryland

I took my car to Midas to have a noisy exhaust checked out. They quickly identified the problem, a section of the exhaust was rusted out and leaking. They charged me $454.99 for the pipe, and then as they were replacing the pipe, they informed me the O2 sensor needed replaced also at a price of $262.90.

Labor was only $94.87. I checked RockAuto.com and could have had both parts shipped to me for $121.07. Midas overcharged me by almost $600 on parts. That markup is way too steep, that is nothing but pure gouging.  That's almost 600% mark up. 

Warning: It's getting ridiculous out there. Be very careful.