Tax?
Is it not possible to (a) get your UK-based mate to pick one up for £xx,000, (b) buy it off your mate for £1,000 instead, (c ) pay tax on the £1,000, then (d) bung your mate the difference afterwards?
By the way, just checked on AutoTrader and Y2K W-reg LS400s fetch from £4,995 (one in Watmough) to £9,450, £9,850 and £9,995 (the other three).
Y2K X-reg LS430s start at £15,980