I went to my local Photo Shop today in order to pick up some chemistry. Way, way in the back, with all of the used darkroom equipment was a bin with about a dozen used SS 120 reels. They were $5 Cdn apiece. Really cheap! They were all in really good shape, apart from the dust, and I bought two as back-ups.
In case anyone is interested, the store is Presto Photo in downtown Quebec City. The website is Presto Photo
No, I have zero interest or association with the store, I just thought that this might be helpful to someone.