I guess I sent for and received one of the last catalogs sent out by Garth Optical. Actually it is a copy of their catalog. It has prices changed and a new mailing address, inserted with pen. I was purchasing a Rack and Pinion Eyepiece Holder that looked very high quality for the time. It set me back $13.95 but I just had to have it for a new scope I was planning. I even did a drawing to scale before it arrived. (See scan) Of coarse I told myself it was planning, but that was a deception, it was more anticipation. I still use it today incorporated into my RC Scope.
Garth Optical was around for quite a few years at mid century. They were located at Springfield, Massachusetts and had just moved to Kendall Park, New Jersey when they sent me the catalog. They were advertisers in Sky & Telescope and Mechanix Illustrated, among others. I did a search and only found a couple of mentions. One advert on Phil Harrington's site, and one on a site with a wonderful old do it yourself scope page in Mechanix Illustrated for April 1957.
As a shock, look at the cost of aluminizing and coating a 12" mirror!!!
Clear Sky - Rich