My problem was the size of some of the orders. Toyota UK got involved on the basis of checking for counterfeit parts. They held up a shipment for about six weeks. When I finally did get the shipment, having been declared as genuine parts by Toyota, lots of bits were missing. Toyota blamed customs and customs blamed the supplier.
I was told that Toyota UK have the genuine parts market fairly well stitched up. There is nothing they can do to prevent individuals bringing stuff in for their own use but they can stop companies bringing parts in for resale.
Just as well I had a large personal collection of the worlds most unreliable Land Cruisers at the time and was constantly needing bits for them.
The big killer was the air freight cost and the only way to get that sensible was to place large orders and spread it around.
As some of you are discovering with Amayama, Customs and Excise as well as Parcel Force still like a pretty big slice.
Cheers
Ian