Let me see if I understand you correctly. You were too lazy to do it
yourself and you didn't shop around, and now you are complaining about
the price. Sounds like you should have done your homework.

Even if you are afraid to install it yourself, there is no reason why
you could not have remioved the old one yourself if there was a working
cutoff valve at the dryer. If not then the charge to remove old dryer
and install a valve and do some repiping there would have been
justified.

And without details of what the install consisted if it's hard to say,
but adding a piece of flex hose and dryer vent stuff could have
potentially been complicated, but unilkely.