I dont know where to buy them but i've been in talks with a client to make an 1:1 Agent smith soon in the future. So i can offer copies of it when i'm done if your interested.
Maybe a good start to a collection for my taste would be Smiths tie and accurate clip, the two different pairs of sunglasses from 1 and 2, the earpiece
and also his weapon from the first film. The nokia phone is used a couple of times including Neo. I dont know the origin of any of these props but you could take it from there.
I want to get a screen accurate NEBUCHADNEZZAR! :love
There was one in Japan made by Hot Toys. It came as ultimate Blu-Ray disc edition and was waaayyyy overpriced (39.500 Yen). Don't know how screen accurate this one was but it looked nice...