Meanwhile Morgans are selling a duplexing A3 network wireless inkjet / scanner / copier / fax with six sets of cartridges for £135 - it's huge and I really don't want to go the inkjet route but it does Apple Airprint and other protocols so might be interesting for someone who really needs that.
later: Just to clarify, this can print up to A3 paper size, but only scans and faxes a maximum of A4. Still pretty useful if you need A3 printing. Thanks to nojay for pointing this out.
Their colour laser printer deals are pretty good too, with VERY cheap consumables, but none of them are duplexing, for that the Ricoh above may be the only option under 150 or so.