I have done this, but oak from France. My main reason was a wanted some particularly long beams that I didn't have here and could not get at a sensible price. These were cut to spec in France. I was however, able to arrange for the lorry to carry some very wide, seasoned and milled floorboards for me as well.
It was three years ago and the delivered price of the green oak (highest grade), including all transport, duties etc was as I recall a bit under £18 a cubic foot. The floorboards were in effect shipped free as the deal was for the green oak, bu their price was less than half what I would have to pay in the UK for good 12" boards. The French haulage company also waited to do a combined load, as the lorry came over with a similarly sized trailer for someone else. And I needed labour at the destination to help unload and stack as the hi lift crane on the lorry can only do so much.
Prices of oak seem to vary a lot. Bar in mind I am DIY not a commercial yard. For very good quality green oak prices in the south east can be anywhere from £25 a cube to £50 a cube plus VAT. Sometimes plus delivery at anywhere from £70 to £200 a load. This was priced late last year for a timber framed house for a commercial project, and for pretty standard sized wood (8", 7" and 6" square, plus 4x2 and 4x4 and 10X3.
It can be a great deal cheaper to import it - but a) you need to factor in that you will spend a lot of time sorting it out, b) you probably will need to speak the lingo and c) unless you are there at loading time you won't see what you are getting, d) it takes weeks, and e) you need to buy a bulk load.
Seeing what you are getting is important IMO. You don't want stuff that is full of defects. So that takes time. Wastage has to be factored in too. I would forget the van idea. Hardwoods are very heavy so van weight bearing capacity will be an issue in worthwhile quantity.
