While I fear this thread may turn into something it shouldnt, I will answer your question as its my guide:
I have been collecting cameras ( mainly pre 1900 woodies and Leica ) for the last 15 years. While many call me a "dealer" of cameras in a derogatory way, I define a dealer as someone who's occupation is selling cameras - thats not me. I am a gear nut like many of us here. In 1994, I created an antique camera website. Over the years, because of the exposure of my site ( it has been ranked # 1 or # 2 on google (alta vista ) the last 10 years for "antique camera(s)" keywords), I started to get lots of offers to buy nice camera items...so I did and I have. I buy what I like, I buy what I collect. Sometimes I buy just to play with it for a week. Then, I sell it to fund more purchases. I have had the wonderful opportunity to buy great, fun gear that interested me, and then I was able to sell via ebay and, for the most part, not lose any money doing this. Does that make me a dealer ? I dont think so, but I know everyone has their own opinion. I have a full-time professional job, a wife and kids.
Also, over the years, I was getting 100's of emails a day ! from people asking me to identify or value their camera items ( everybody thinks a camera older than 20 years old is an "antique" ). For years I did this for FREE on my own time, at my own costs. But one day I decided I should charge for this service because my free time went to nil when I had kids, so I set up a cheapie "appraisal service."
Then, I will still getting too many emails to handle, so I set up these FREE camera and lens price guides for TWO REASONS.
First, so people could look up the value themselves for FREE
Second, I set them up with ads ( ebay and google ) to help defray the costs of my internet service, cable service, server space etc.....
Since I was already tracking prices for my own collecting purposes, creating these guides was a natural extension.
So there you have it, that is the purpose. There is no deeper or more sinister plot behind the guides.
Lastly, I frequently get flamed that my prices are low. As I explain on every page, these prices are mainly from EBAY with input from dealers sites. So, before you claim my numbers are low - just do a simple search on ebay of completed items and you will see for yourself my values are right in line with ebay AND I state on my site buyng from a dealer will cost 10 to 20% more.
Dan