There is alot of labour involved. I did mine myself, not something I would rush into doing again!
Might save a bit on the price if you removed the old carpet, glue and floor yourself. A dirty job but easy enough.
I've got the rubber one on mine (aaz) and it leaks in the bottom right corner! I have just received another one and going to try again. However I am not sure whether to use sealant or not. I did use sealant last time but wasn't sure if I'd used enough or if I'd I applied it correctly. Might even be ...
I don't think you can get Fellows spares anymore unless they crop up on Ebay etc. Fellows cookers seemed to be swapped out for Spinflo 2 cookers but I don't think they are available in this country anymore but can get them in USA and New Zealand. There are a couple of threads on here about it. Howev...