My 100-2s was rebuilt by a Howard’s rv in California .. 7 grand cash
4days work . it’s been working great. I believe mine is a older design with coils outside the tank. He had a new tank manufactured coiled the tank himself ( not as pretty as the original machine coiled) , But the more insulation. I learned a lot as I watched and helped him combine my working burner with new tank after he rebuilt the webasto bearings. as to The tank was rusted and not reparable according to a couple sources. I think he tossed mine in the trash bin.
My for a new one it’s built from my old parts in a new white box was 8 grand exchange no labor .. I send them my old they send me a new rebuilt using my old parts .. about 2 weeks lag time. Your “new” rebuilt offer is better. Btw it took a couple hours for two of us to pull it. 1500 is cheap for the work done. We are full time and with the knowledge I have now and acces to a new tank and a shop it’s doable but it will take a couple days.