Understand completely.
No one likes seeing money fly out the door...
That's why I push as hard as I can to change the way people look at HVAC purchases.
Sure find the lowest bidder you'll save lot's of money....up front....then all the BS that they didn't mention they throw at you by saving money up front hit's you in the face..(hidden cost, labor mainly when you thought you had a warranty)
The rolls eyes for home warranties was for a reason....they are notorious for not caring what work get's done when someone has a problem as long as it's "fixed" and it cost them the lowest amount.
The main thing I push is find a contractor that's knowledgeable, respectful, trustworthy...ect...It may be hard but then you don't get hit with hidden cost. You know the cost up front and you know your covered long term with no surprises. All mechanical equipment breaks down....that's why warranties especially labor are important. The first time you have an A/C comp. changed and see the bill for labor only the small monthly charges will seem like a far better choice.
The main problem with builders is they don't care. They get bids looking for the lowest bidder....then two guys and a truck come out to install a multiple $1000 system with a pocket knife and some caulk. Then the lucky home owner get's about 2-3 years into their new home purchase and suddenly the A/C conks out. Then you start doing research and find out nothing in the system is correct.
ASHRAE did a study along with state energy dept. that found 70% of homes evaluated were considered running outside of normal conditions...to small of return vents, inadequate air delivery, not enough air flow, over/under charged...ect...really disturbing actually.
That's why the push for things like NATE certified technicians....It's equivalent to ASE....basically it means they can pass test...that doesn't mean they won't make mistakes though. The more complicated the system get's the less contractors you'll be able to find that can truly fix the system....and they will never be cheap. $100-$150/hr is common depending on location. That labor adds up quickly.