The GW market on eBay

A recent project of mine has been to custom build a Cypher model from Dark Angels bitz purchased from eBay. I know that there is a metal Cypher model and that the rumour is that a plastic/resin version is to follow however I'm not keen on metal models and I wanted to explore using eBay to get the bits I needed. I will cover the building/painting of my Cypher model in the near future but the purchases I have made recently have highlighted the versatility of the GW eBay market at the moment.

My first experience of this when last year when Bob told me that he bought some Space Wolf bits in order to get a particular 'thing' for one of his units... and he then sold the rest of the bits on for the same price that he bought them. Having bought my Cypher bits from what basically seems to be 1 seller selling individual parts from the Dark Angels Chapter Upgrade sprue I am wondering if there is a market to make a reasonable return from buying these kinds of kit from GW and then re-selling as individual parts.