The closest I could get to that would be
www.aviationconsumer.com. You have to be a subscriber to get the good stuff, but they have a quarterly subscription option that costs just $20, so it is not too expensive to get in to. They have all the buying guide articles about different aircraft online, as well as roundup articles that cover things like "Fixed Gear Singles", "Aerobatic Airplanes", etc.
It is not a web site, but my friend and insurance broker Scott Smith has written a book (published by Motobooks) entitled "How to Buy a Single Engine Airplane" which I think does a good job of covering the spectrum of single engine airplanes, as well as buying tips, etc. The book is available at
www.skysmith.com
Kevin