Miele's are nice, but can be a pain to re-sell as they get so battered!
The S5 I got for free worked utterly fine once I changed the bag and filters so it stopped overheating itself, but the plastics were destroyed. Not a problem for a machine you want to use, but makes selling it impossible!
And +1 on spare parts prices. On an S5, the silver plastic pedals and trim that run around the back of the machine, that always flake and scratch and look shite, £20ish per piece from Miele! Infact most parts bar bags are only available from Miele. Q had some bits in a long time ago, I bought some wand button kits which were ace, but there was buggar all other stuff. Things like motors and cord reels, your best bet is buying a scrapper machine and hoping (I have an S5 motor in the shed just incase, although it's not great)