Know what you mean about Acorn. By the time you've coughed up for the digitising (probing) version and the expansion board, you are at $1000 before you even find a PC to run it on. Then the wireless MPG is another $240. It works well and the support forum is very good, so I'm very happy with it. Depends if you have the dosh available.

The AXBB looks pretty interesting. No experience of them but they seem to have all the bumps in the right places and the pricing looks attractive.

FWIW, they also seem to sell several different encoders. Presumably they will be compatible with the controllers and the pricing seems similar.

That looks about right for the kit of parts. I assume you have a main PSU from the original system that can supply the bulk power at around 140Vdc or so? I ended up getting a 120V 3kW isolation transformer from Screwfix and removing some turns from the secondary to get the right output, as the original 3 phase transformer was the size of a house..