Transit owner here. £2.5k for 8yrs old with 79k miles. Now 120k+ miles at 14yrs old.
Bought the least rusty one i could find and it was fine for a while but it’s been fairly hefty welding bills for the last three MOTs, hopefully not next time as I think most of it’s been replaced by now! Mechanically great, only expensive bit has been a fuel pump. Mostly simple for the DIY mechanic and loads of parts out there from scrappys if required.
Look for rust in the sills, under the passenger seat, rear suspension mounts especially but it will occur anywhere. Spare wheel carrier will rot away completely but that’s not an MOT issue.
Mate scrapped a 2009 Vito due to rust.
Hiace is a good shout but for £2k you’ll be looking at really old and/or very high mileage, they do last though.
Best advice is choose on condition rather than age/miles, most vans are made of cheap steel and deisgned for a short, if hard, life and so rust like buggery by the time they are old enough to be in the price range.
And what Chester says, second-hand van salesmen make used car salesmen look very good indeed!