Hilary Stone's website in the UK (google Hilary Stone bicycles), the Paceline Forum, the Velocipede Salon forum, the Classic Rendezvous website and forum, and the Road Bike Review forum.

CR has been a list and site for fans of classic lightweights starting at least in the late '90s, and is full of very helpful people. I'm on that as are a number of others here. You have to use your actual name, there are rules in that forum. But you are also likely to find collectors with bikes to unload. You'd need to be a member, it is not a sales site. However, a LOT of material goes back and forth between members.

Also, keep in mind that Ebay offerings change every day.