Some are still available, but I bet not for long. I bought a couple. They only have had one or two silver gelatin prints of each. For instance, I bought Ornette on violin, and Clifford Brown with Jimmy Heath, and they are now marked as SOLD OUT.
I called Mosaic, and exchanged emails with M.C. The silver gelatin prints won't be available after these are gone. The ones they still have are 1994-1995 darkroom prints.
The contact sheets are amazing, and are an intimate look into Wolff's process, but I didn't buy one. Maybe I should. $500 is steep, but they are unique. I doubt they'll be available again.