I am also focussing on 1920s Cthulhu and Delta Green, with the exception of Down Darker Trails because it is excellent.....and probably Cthulhu by Gaslight if it is released this year. Not keen on other Cthulhu eras, for the most part.IIRC you're in Aussie or NZ, right?
I know Dark Streets is good, but I am trying to reduce my Cthulhu gaming stuff to the 1920/30s and Delta Green. I do hang on to Down Darker Trails, but I picked that up mainly for its historical western content. I'm just tired of throwing the Mythos into everything.
Anyway, if you are NZ based, to you trade on the NZ RPG Auction site on Facebook? It has a rattling trade, I think, and you have so much less overhead cost because postage is local. I’ve managed to sell quite a lot of books there in the last couple of years.