Minuteman Scale Models lists the Bridgeton Car Shop and Bridgeton Machine Shop in Sn2. To my knowledge these are the first B&SR structures to be offered in S-scale.
http://www.minutemanscalemodels.com/category_s/60.htm
Minuteman Scale Models B&SR Car Shop (image from company web site) http://www.minutemanscalemodels.com/category_s/60.htm
Minuteman Scale Models B&SR Machine Shop (image from company web site) http://www.minutemanscalemodels.com/category_s/60.htm
I’ve not seen these models, so can not comment about them. Please comment if you have acquired or built one of the models.
Sn2 Trains 
I have both kits and have begun building the machine shop. It’s a very well engineered kit. So far the fit and instructions are a joy to work with.
Goodd reading