The UK/Euro market is so odd to an American. I just quoted out this bass and you could order a new one for about $7500 US from the right dealer. With the best monthly special, it would be more like $6800. That's not far from the eBay price you referenced, though it doesn't cover any of the costs associated with importing to the UK. In the US, the used bass would probably go for $4000-4500 in a private sale.
In any case, a European asking price of ?4.000 doesn't sound out of line. If you go back five years to when I most closely followed the Alembic markets, it was very common for the UK value in pounds to equal the US value in dollars for used instruments. The difference between an '08 and an '09 is nil.