I'd go for an HP business model like this one (dunno if it can print on A3 paper check the specs):
Just type 'laserjet' in Ebay. In HP printers the drum is included in the toner cartridge. So whenever you change the toner cartridge, you replace the drum. I have a Laserjet 5P from 1995 which still works excellent. If think you are better of with a 2nd hand printer aimed at business use with a low page count then a new cheap consumer printer. I get around 4200 prints from an original cartridge which costs me around 40 euro (surplus on Ebay).