This story's a bit different.  Usually we name companies when they've done something wrong.  And while I do feel the company Leona used charged her too much, I don't feel we're justified singling them out.  They may be the most expensive company, but they let Leona know the price before hand.  And there's no industry standard, so it's a buyer beware situation.

It's hard to know if you're getting ripped off or not when it comes to hiring an ac/heat repairman.  Some charge you a "trip fee" and most will charge a diagnostic fee to find out what's wrong with it.  Doing that with several companies in hopes of shopping around just doesn't make sense.  That's why you should use a reputable company - which has been recommended to you.

But as for the bigger jobs, like buying a new ac/furnace, I would recommend shopping around.  Keep in mind, cheaper does not always mean better.  That's why the "Air Conditioning Contractors of America" have put together a checklist to help you determine which company to go with.