most of my colllection are just models that are still in production like the current plastic chaos marines and loyalist dreadnoughts. i did recently buy the old Space marine terminator captain for a Captain Invictus conversion and also a Cypher model. OOP models that i would use if I still played Nids would be the 3rd edition 3 Tyrant Guard, 3 Biovores, 3 Lictors, 1 carnifex, Old One Eye and the old Space Hulk Genestealers that were reboxed for the 3rd edition nids (have about 28 i think though some have broken).