Bruce,
I replaced our shocks, airbags, brake chambers, and rubber brake lines in January. It's a very easy job with the wheels removed. Jon's estimate of time is very close to what I experienced also. From my Prevost Invoice, replacement shocks were $39.23 and air springs were $129.90. I purchased the brake parts from a local truck parts outlet. The service chambers were about $30.00 ea, the spring brakes were $135.00 ea and the brake lines averaged about $7.00. I checked with the Prevost Service Manager in Calif regarding Konis and his advice was they're not worth the expense but they would be glad to sell them to me if I wanted them. We experienced a significant ride improvement with the new replacement shocks. So far on our trip the leveling system has been tight as a ...............
It was a fun project and I learned a lot about the bottom side. Would highly recommend you purchase a PAIR of air jacks from Harbor Freight or Northern Tool and a set of Jon's jack-stands if you haven't done so already.