It's difficult to say because we've had a couple of ex City Link Sprinter in the past direct from auction with similar mileage and both have fared pretty well. On the other hand we bought another ex-lease from auction (not ex City Link) must have been driven by a t**t as it was a bit of a pig with only 100k.
If all seems well with it, I wouldn't be put off buying it because it's ex City Link or Yodel.
A new clutch with flywheel will set you back £400 plus a few hours labour. The real killer is a recon gearbox which will probably set you back over £700 plus labour - just check the gears go in easily (with and without the engine running) and that they don't pop out as you driver along (assuming you can drive it beforehand - if it's an auction vehicle then you just have to take that chance).