Casoolt, does it have to be a 2906? - Why not a
2904. If you skip past the first few pricerunner, kelkoo and dealtime webshites then you'll find a few for sale in the uk.
I always thought that 2904 was for PC and 2906 was for Mac although Ezmans post is an interesting and useful find.
I bought mine new about 9 months ago from here
http://www.newlogic.co.uk. I found it through ebay but was shocked to find out that the shop was 5 minutes walk away from where I lived so I popped down there myself and got one.
They still had 3 left sitting there collecting dust after I had bought my one, might be worth giving them a call.
The 2904 interface has a High Density 50 pin connection but luckily I had an old 50pin HD to 50pin Centronic cable lying about.