I believe the Taig chucks will fit the Sherline's too. Taig accessories are also very well made but tend to be less expensive than the Sherline version. They have no anodizing and often aren't as polished as the Sherline, but I have found the Taig chucks to work quite well. And while I have used several Sherline accessories with my Taig (like the mill vise and the 4" rotary table - things which Taig doesn't make) and they are very nice, I have never used the Sherline chucks, so can't directly compare.
The Taig 4-jaw is 79.50 (and you can always get it for 10% off from Nick Carter Tools).
The Sherline 4-jaw is $147.42. 20% off would be nice, but I didn't find that in my quick google search.
Just to give you an example of the price difference.
Kim