I highly recommend Diderick's website-
www.zeistbouwplaten.nt . He has an excellent selection of models, many that are hard to find. I recently purchased from him the Guggenheim in Bilbao and a hard to find Gloucester Cathedal by Rupert Chicken. This was the first time that I had seen either of them on all of the model web sites that I visit. He not only has great models, but prompt service. I check his website every several days for new models.