All our ZS's are getting old, I paid £4150 after a bit of haggling over the conditions of the alloys. That was just under 4 years ago and 30,000 miles.
Had the belts done and the big service and apart from pads, disks all round, tyres, oils etc. all that I consider service parts, thats all its cost. Apart from a few tweaks!!
So even at a £1000 a year depreciation its not bad, but if you can still get £2500 to £3000, the sums come out well.
Plus you get the smile factor, I think all the Zeds are great value.