Hi Javajude, i live in Hounslow, although i know of trade sales as i looked there before ordering from a UK Lexus dealer. The prices quoted at Trade Sales are for the basic spec. If you want an Auto add £1200, if you want metallic add £300. You then have to add their indemnity charge, road tax, number plates etc. in the end it does not end up being such a good deal. They do have really good deals on some cars but not the Lexus range.
I was also told by Lexus dealer that all IS 200's that come in to the country need to have their alarm system configured to the Thatcham requirements. This can and is only be done by Lexus GB and therefore the imports do not have the same security setup as UK sourced. This was confirmed to me by Lexus Insurance who said they would not even consider insuring an imported Lexus.
All in all, i paid about £1000 more at a Lexus Dealer than at Trade Sales. I think it was worth it, especially as i got the three year warranty and three years RAC cover including Europe!