I would say that £200 sounds about spot on - but you will need to come across a buyer that needs one.
The HDR-1's STB-C/PUC table can be updated via PC, and as it is light and rather compact (and portable) it is very easy to do so by bringing it to your dealer. Current owners of BV3/Avant/BV5 can, by adding the HDR-1, have access to all STB's currently available - I doubt that B&O will issue another IC for the STB-C.
Sure, you will have to hit V.MEM (or V.TAPE) followed by the green button on the Beo4 (unless you have the Beo5, where it all can be pre-programmed) to watch DTV on an older set - but you get STB control for all the boxes.
And you get the ability to record a tv program...
Roger