honestly bro,
im sure there is no set price of removing a broken/seized bolt, so even asking for a quote would have left you in the exact same place...

charged by the hour to get the job done...

most shops charge $85-100 for a hourly mechanical rate..
so to you that may seem a bit steep, but you also took up 2 hours of the day on their lift..
someone elses car could been on it, getting work done..

not to sound like a dick, but think about it from their perspective...

they run a business, if they charged everyone $30 to be one their lift(2hrs a day) and use their mechanics to fix the car...would they still be in business??