Hardinge, Royal, and a few others are making them still.
But, I have to say - while Boss Tool Works's stuff is priced in the "painful"* zone, I have never once been left feeling that any of their product was inferior or lacking. It hurts to put up the scratch to purchase it, but you'll forget about it over time when you've come to use their stuff all the time and never have to wonder about it.
( * and yet, less than Hardinge, Royal, and others )
Having said that, NOONE'S collet blocks are as good as I would want and have found over the years that you have to fiddle with ALL of them to get them to repeat. Frankly, none of them do. It more learning to indicate each time you release and clamp it. Debris/Chips can enter the collet seating lands, the collet itself, or any other sliding interface to make one's day less than enjoyable if not enough attention to detail is paid and adhered to.
Disclaimer - I use a bunch of BTW's stuff. Happy customer, otherwise not connected.
I cannot imagine why you would be looking... LOL.