There is at least one name in photo gear history that probably won't ring any immediate bells. His name is Siegfried Franz Spira, or simply Fred, to those who knew him personally. I'm not among them, but I was certainly aware of his company as a kid in the 50's and 60's, with a head full of wishes for what he offered to all of us on the lower branches of the spending tree. If the company name of Spiratone is unfamiliar too, then I'll leave you to research that on your own. The company spanned a 50+ year timeline starting in 1941, and some of their gear was truly wild and wacky too.
If you've had a glimpse of Spiratone gear as-sold in its heyday, then you might have been one of the many that dismissed anything they offered as cheap low-end products that were mediocre at their best. You would have been partially right by that assumption, as they were absolutely cheaper than almost all of their counterpart's products from the major manufacturers, and even most of the 3rd party makers. I think it's fair to call Spiratone a '4th party', since they manufactured none of their own hardware and simply sourced and re-badged some of the lesser known Japanese maker's products from the 1950's on, under their own 'house brand' name. Some of their lenses were dressed-down a bit, so you weren't paying for rubber grips, but knurled or machined metal barrels. Other lenses and gear were less 'frilly' and looked rather plain, as style wasn't part of their selling point.
The portion of your assumption that might be less right, is that their products were mostly mediocre and unworthy of owning if you were a 'serious' photographer. Lowered manufacturing costs didn't have to mean lesser optical quality, or barely passable build quality. Some may have been close to that, but by no means was that a given for everything they sold. Insiders and pros could smell something cooking in the early Spiratone camp, and a few sleepers emerged from the lineup over the years. The owners who did buy these were perfectly happy for the rest of the world to be blissfully ignorant of what they missed by not buying them too. No one wanted to see prices go up because they suddenly became sought after and better known for their performance.
I know of one newspaper photographer who would never pick up his Domke bag unless his favorite YS 135mm f/1.8 was in it. It was his bread and butter news lens for the night shift, when there was precious little light to be had and one had to shoot from a distance. It wasn't a situation where you only hoped you got a usable shot, or you'd have to face your editor when you've got no shots at all. These were the times where police had to keep all of us with cameras from getting in too close while they're working their serious accident or murder scenes. Non-telephoto lenses or zooms with slow apertures just didn't keep you employed in those days if you had to shoot film stills at night.
I haven't made it a point to seek out many of Fred Spira's lenses, but I'm always open to pick up the gems when they show up. I've yet to find my own 135mm f/1.8, but there are a few others that I've found in various guises. Since the company was a distributor with a large catalog of products, they had a long list of manufacturers supplying them in much the same way that Vivitar, their later rival, has operated since it's inception. You can find many of these same Spiratone lenses labeled under their original maker's names, as well as a slew of other rebranded ones. A fair portion of the 'Zebra' line of preset lenses were made by Sankor, and were also sold as Accura or Vermar and a few others; and many of the 'Minitel' mirror lenses were made by a wide range of makers - including a supposed Tomioka model that was a simplified T-Mount version of the Yashica 500mm f/8 made in C/Y mounts for both the Contax and Yashica line of film bodies of the 70's-80's. The 500mm lens I have and have posted the samples for, is one of the '532xxxx' serial number lenses that's been reported to be the series numbers made by Tomioka.
The first two lenses/samples I'll be posting, are the Spiratone original 3 set-screw T-Mount versions of the 105mm f/2.5, and the Minitel 500mm Mirror lens. The Sankor-made 105mm is a 16 bladed buttery-smooth-bokeh performer that's very sharp by f/4 and almost overly rich in color saturation and contrast; and the 500mm is more of a swirly-donut specialty that oozes character - but - it won't ever be razor sharp, although it's extremely consistent in IQ from corner to corner at its constant f/8 aperture.