another thought... but it only applies to buying remotely...
back in the early internet days of 1997, I came across an ad for the Olmo that I now own. It was offered for sale by a fellow in the eastern USA. I talked to him, but wasn't sure about the deal. He offered to put me in touch with a fellow he had recently sold another bike to, and this fellow was able to give me some confidence in the seller. So, getting in touch with with someone else who has dealt with a prospective seller isn't a bad idea.
A side benefit is that the person acting as a reference might ride the same size bikes as you, which can be a useful thing! I ended up putting this fellow in touch with a local shop that was selling a nearly NOS Paramount.
As far as the Olmo, it had a bit more wear than I expected, but it's been a great bike! Lots of pantographed parts, and it's not too pretty to ride.
Steve in Peoria