Where to start?

I need a little jump start from some of you experts. I am trying to research and buy a set of quality used bookshelf speakers. The only one I have been able to listen to is the B&W CM5, so this is my reference point. Has anyone possible put together a spreadsheet of specifications? If not, are there sites that do a good job of comparing? I guess the real question is, what is the best way to get started?

Thanks,
dw8ite