As it happens I was actually offered a Xerox Lisp Machine to take home when a university department I was associated with was throwing some old kit out. I was living in a tiny flat at the time so it wasn't really an option.

However, now we have plenty space and a property that is very difficult to heat and we need heating ~6 months a year, changing the property is not really an option (planning restrictions are really tight where we live - for good reasons, and any improvements would be incredibly expensive) - BTC room heaters might actually make sense....