Ah yes, Owen Davies. I initially heard about this place through ads in Trains Magazine in the mid-1970's, right when I began getting into trains. From my house, the store was a one CTA bus ride away. I remember the Pennsy calendars hanging in the stairway and the place was very packed with railroadiana in what was essentially an apartment in a 1900 brownstone. I believe Owen had already passed on - I recalled only seeing his wife and the assistant. They always had a classical music radio station playing in the background and the one thing I thought was strange was a picture of Lenin hanging in the back room (the kitchen). The one purchase I treasured most from that store was a March, 1944 issue of the Official Guide with a routing cover sheet from the North Shore Line. I was able to get that for $10. I devoured that Guide on the bus ride home. For some reason, I never went back there again after purchasing the Guide. I heard shortly afterwards from my high school rail buddies that the store moved to Oak Park but I never had a chance to go there.
There were two additional non-museum related railroadiana stores that I patronized. One was the Broadway Limited Antique Company in New York City, in the same building where the Official Guide was originally published. Among other things, they had a substantial inventory of original Official Guides for sale, and I bought a couple there. The other store was operated by Arnold Joseph, who had a store in one of the older office buildings on Broadway near Pennsylvania Station in New York City. I dealt with him by mail a number of times, but I also visited his store twice. I bought a number of Official Guides from Arnold - my first trip in 1980 yielded a dozen issues and he threw in a copy of the first Amtrak timetable as well as a copy of an AAR publication which listed all passenger train names in the US in 1950.