There was a pile of Chore Horse/300watt charging set spares in the well-known auction site this week, starting price 60 GBP and I was considering a bid (30 GBP shipping), but eventually decided not to bother as I'd never need about 5-each of new valves, pistons, brushes, and sets of gaskets/seals.
It went for 170 GBP + shipping, which was well over my limit anyway.
At some point I need to get the toolbox and funnel (etc.) for mine. (It came in a crate with the cover and exhaust hose/silencer but someone had extracted the metal box with all the other ancillaries.)
Chris.