You have several options:
Option - A
You can do your own cursory patent search for free at www.google.com/patents/ or at the U.S. Patent Office website, www.uspto.gov/patft/. To see the drawings, however, you'll first need to download a free TIFF reader, which the Patent Office makes available through a hyperlink on their website.
Option - B
For $500 you can have me do the patent search for you. To get started, you'd need to pay an initial $250 (check payable to Bob Harter) and explain your idea to me by letter, phone, fax or e-mail. The remaining $250 would be due upon my providing you with the results of the search. It usually takes less than a week to complete a search.
Option - C
I usually don't recommend this, but you can file a patent application without doing a patent search beforehand.