Yeah Steve, I'd be looking for the whole Dynaudio stuff out of a wrecker too.
Mine's a Sept '06 car - haven't a clue how many speakers it has, and what's this amp under the seat lark? Surely they wouldn't fit that to non-soundpack cars, but it might be had quite cheaply and the wiring may already be there for it??
I remember in my MKIV as soon as I replaced the VW unit with a Becker, it sounded a million times better on the standard speakers alone... so I'm hoping a bit of OEM tweaking of some sort and a RCD/RNS will improve matters.