Ed Soetje from Bonanza came out to our house and was very professional in fixing an A/C duct and some insulation under our house. He took extra time to inspect my furnace and A/C (at no charge -- even though they are paid by the hour). He explained which filters were the best for efficiency and durability.
He also recommended the best-priced stores at which to buy air filters even though he had some on his truck that he could have sold me.
All in all, a very pleasant experience.