Transmission Fluid Change for the 3.5 V6 (Not 2.4) ANH20 Alphard / Vellfire uses ATF WS and has been quite hard to get hold of.
I have seen a Toyota Dealer selling it for £25 a litre on amazon, yes you read that right. As its hard to get hold of they are making the most out of it.
I have just bought 7 litres for my Series 2 Alphard (bear in mind Alphard 1st series uses different fluid!!!)
https://lexuspartsdirect.co.uk/product/lexus-genuine-ws-atf-fluid-1l/
Lexus Parts Direct sell it for just over £10 a litre with a few quid delivery. A pound cheaper that Toyota Parts Direct. lol
Sometimes this does go on back order as there is a shortage ( an additive shortage) so get some now or put yourself on back order if they run out. Other prices i have seen are £15 per litre, so Lexus Parts Direct have a decent price.