With the money you'll spend on those ads, you could buy a new truck, have it professionally lettered and park it in a prominent parking lot near a busy street all day. You might get more calls and you'll have another truck as well! I've gotten more business from a couple hundred dollars in signs then I have from the yellow pages. I don't know about Colorado, but here you can spend thousands of dollars on a Bell South Ad, Then there is Talking Phone Book, Then there is Verizon, Then there is Ads for books in your other service areas.
Its been a year since I've had an ad in the yellow pages, and it hasn't hurt my business. People who fill out the estimate request form on my site, or call from my site have usually gotten past the tire kicker stage.
Your business may be different if you are focusing on commercial work, then maybe the yp's will work for you.
Did I break even or come out ahead on my yp ads? Yes, but what if i had taken that money and paid some one to call my customers to thank them for there business, or spent it sending thank you cards or a small gift?