So I PM'd Wanstalls on CGN and they "answered" my question with another question: Why do you want a list of retailers?
I explained I am looking for a XR9-L Onyx (not currently in stock at Wanstall's) and am shopping for the best deal.
I thought a distributor would want to supply such information, or at the very least have some sort of obligation to provide a list of retailers that stock the product that Wanstalls themselves distribute. I'm just looking for the best deal on a model that Wanstall's doesn't currently have in stock.
Hopefully I can get a list at some point before I just bite the bullet and go through IRUNGUNS.