M.F.
I recommend going with a known, trusted company like Sears instead of just going for the cheapest. We had our ducts cleaned before our daughter was born and used a company that advertised in the Val-Pack (can't remember their name, but they advertise under several different names). The guy first tried to scam me into an additional $900 in "mold treatment" because he said he found mold in our ducts. All houses have some mold and I'm allergic to mold, so if we really did have an issue, I would know it. His "mold test" was a tube of some liquid that turned purple when he put a swab in it. For all I know, it was food coloring. When I refused the additional cleaning, they refused to use sanitizer in our ducts, even though it was stated on the coupon that the deal included sanitizing. He even tried to tell me we would have to pay extra for them to clean their equipment, so as not to spread our "mold" to other houses. Basically, I paid the price the coupon quoted and kicked them out of our house. Now here's the real stinker in all of this-about 4 days later, I got a call from Southwest Airlines that someone had used my AMEX card to buy a plane ticket, but they canceled it because they didn't think it was me. I called AMEX that night and discovered an additional charge for a locksmith made about an hour earlier than the airline ticket purchase. I paid the duct cleaners with my AMEX and they were the only company I paid using that card that was not a well-known, trusted and secure company. All the other recent purchases on that card were national corporations, but all the fraudulent charges were made locally here in Phoenix.
The next time we have our ducts cleaned, I will only use Sears and pay whatever they want, because it isn't worth the hassle of scams, theft and just letting shady people into my home to save a few bucks.
Good luck!