I've got a 2006 Combo with the Isuzu 1.7 cdti, which I've had since 2009. Euro 4 and does about 36 mpg with roof rack etc. Cost £3400 with 97k on the clock in 3 years. I've taken it to 162k and it carries a load of weight, tows stuff etc, couldn't fault it been brilliant really.
Other than a couple alternators £300, one timing belt change £500 and one clutch flywheel kit £700 it's been fairly minimal running costs.
Last financial year was about £220 of parts including two tyres and a battery. I do a fair bit of maintenance and all servicing myself. This is pretty much bang on average running cost per year.
For the last 3 years I've expected it to fail the MOT catastrophically but not yet! I had a patch welded this year which was the most expensive yet at £200 but that's it, plus servicing.
In my opinion it costs less to pay £250 a year on maintenance than the depreciation and finance costs of something newer.
It just depends what you don't mind driving.