As a fairly new member of Agon. I can understand your trepidation.
Agon is not responsible for your transactions. You have to exert due dillegence.
I think you have done well by steering away from purchasing equipment from sellers with no prior rating/feedback.
Though I have to say, all of the sellers on Agon, that I have bought from, have been most accommodating and forthright and have allowed me to demo the equipment before buying. That was something I was really surprised by- allowing a perfect stranger to come into your home to listen to your equipment.
So, if you see something that catches your eye, but the seller won't be flexible, then politely decline the offer and wait for the next seller. I can promise you, you won't be sorry.