Oh the memories.
Many years ago, I lived in Chicago. Darkroom Aids was an absolute toy store for photographers. Beyond the usual new stuff like paper, chemistry, lenses, sinks, etc., they were an absolute goldmine of all things used for the the darkroom. I bought my push-up Omega DII with a 150mm Schneider Componon, Lens cone, and carrier for $300 there ! Better still, they had a wall mount turnbuckle for it. I still use it to this day. I also bought an 8 foot stainless sink from them, and the store manager delivered it to my home. That is still in use today as well, though nowhere near Chicago.
Terry G. ran the place and was a walking encyclopedia of all things darkroom and all things Sinar. (He was also an active shotgunner.) When DA shut down it was a dark, dark, day. It was the last of the great darkroom-focused stores anywhere for a thousand miles. It was THE place to go hang around with other darkroom nerds, pros, and people that just plain loved the craft. I bought my first M645 used from them and used it for some years before upgrading to a 'Blad.
Terry went on to work at Calumet until it folded up as well.
Many of these things can still be found on line at various company websites and eBay, but there's nothing that replace the "hanging around" ethos found at places like Darkroom Aids.
Thanks for the memory