Big Pockets and SVP are doing the Pioneer 104 (the OEM version) for £250 - £260 anyway so I suspect that any saving you might make on in ordering it from the states will be swallowed in shipping costs, not to mention the pain in the arse if it goes wrong or does not work when it arrives.
The difference between the A04 and the 104 is minimal:-
A04 is shipped with cable, mounting screws, blank disk, software and a pretty box the 104 on the other hand just comes with software and a plain box.
SVP also do a nice (cheap) line in CD-R/W and DVD-R/W media.
I have personally never ordered from big pockets so can't comment on their service.
SVP have always given me excellent service and I have ordered from them many times on the odd occasion when there has been a problem it has been resolved swiftly and efficiently.
Im sure other places in the UK are selling the A04/104 for similar prices.
SVP communications :-
http://www.blankdiscshop.co.ukBig Pockets:-
http://www.bigpockets.co.ukHope this helps