It may depend on what brand of projector your interested in. Most dealers don't sell any and all brands. Just like any electronics place. They have their line of products. I was looking at the Sony HS-20 projector a month ago. I started with using the google search site. I just typed in Sony HS-20 and read through the links.
Here are a few links that I found of interest.
http://www.projectorcentral.com/home.cfm
http://www.projectorcentral.com/proj...calculator.cfm
That is off of projectorcentrals site but very useful.
http://www.mountsandmore.com/
http://www.ritzav.com/index.html
I got my Chief ceiling mount and draper screen through ritzavs site. Very good price and three day shipping was cheaper than ground.
http://www.oade.com/index.html
Oades quoted me $2795 on the Sony HS-20 projector. But, I went local due to a fear of issues with a potential projector purchase. I actually got the Sony cheaper going local and the store that I purchased it from. Is an authorized Sony service repair store.
http://www.videogon.com/
I didn't even know Audiogon had a Videogon....But they DO!
Hope this is of some help. Also go to AVS Forum. These guys are nuts for the most part. But, have some very useful information.
Good luck and have fun.