If you want up to around 3-400 USD I might be interested. If, on the other hand, you're looking north of that value I've decided to just save my money for a new PPC motherboard. I currently have a OS 4.1 Classic A1200T and have always wished it was my A4000D that was running OS4.1.
On the other hand, if you're interested in a trade, I have an A1200T with a 68060/50 BlizPPC 603e/233 w/192MB RAM, Mediator 1200SX, and several other goodies that I may be willing to part with in order to build out my A4000D OS 4.1 Classic machine.