Just picked up my grain, and I'm glad that I didn't go making any promises to people, as I ended up paying €1 per Kg. The current market price is €600 per ton, but that's obviously if you getting a much larger amount, and not the €100kg that I got. I'll see if I can get them down a bit in the future, but still happy with the price, and it's fair enough that they seemed happy to deal with the homebrewer at all, when you see the size of the trucks coming in and out.
I took a small trailer, and put a new big yellow skip bag in the back to catch the grain. I had thought of the wheely bin/van combo, but the trailer seemed like the easier option. If you are putting grain into a wheely bin, you will need some sort of ramp to get the bin back up onto the van, as a bin will be heavy and needs to be out of the van, for the grain to drop into it. Then for transporting the wheely bins in a van, you will either need to make sure that they stay standing up, or if you lie them down in the van, that you can keep the lid closed.