Would have to give Amayama a big thumbs up myself. The only time they made a mistake with an order I placed, I emailed, they replied and DHL'd the missing part to me at no extra cost.
Reason why they are (often) so much cheaper that Yota UK?
they are wholesalers/ distributors selling at non-EU trade prices; they charge a much lower mark up on goods basically that Toyota charge for one off 'man in the street' orders. Basically they buy for less from Toyota in the first place because they buy much larger quantities than your local Toyota dealership does. There is nothing dodgy in this, I see it myself; when I 'bulk buy' certain products direct from the manufacturer, the discounted price can be eyewateringly less than if purchased from the wholesaler even if in the same quantity (by eyewatering, I mean the difference between £200 and £50 for the same item, when you factor in a % mark up for sale of perhaps 100%, that means massive savings, but comparable profits. Jig it a little further, it means the business can increase its margins and still sell for less).