Mark Richard is a broker who deal with lots of imports including alphards but plenty of insurers cover them, admiral, direct line and NFU to name just 3.
We have a Granvia the alphards predecessor, fantastic vehicle we have had it for 7 years with little trouble ( 1 seized brake calliper and 1 set of shock absorbers), this on a 2000 base vehicle.
No problem getting the parts and when i did hit something and needed a new bumper we got one in from Japan with no problems and it was very cheap, my garage said cheaper than one for a ford car. BTW the garage is just a back street garage no need to go to a toyota garage.
We had a new conversion as described earlier.
the Japanese imports, Nissan or Toyota are about the same size as a VW but are almost always automatic and bit heavier on fuel.
The base vehicle is people carrier so much higher spec that a VW conversion.
The only thing i would say that is a disadvantage is, when we got ours you could only get back rising pop top roofs, nowadays you can get front risers like the VW which give better space in the van.
So with your budget you should be able to get a front riser if you are having a pop top, if you are having fixed roof then no problems
If your looking at a Japanese import also look at the Roadtreks & pleasureway.
We have a 170 Popular Roadtrek which previous owner imported from Japan, made in Canada, petrol & automatic but it's a great little camper we love it.