In the US, I think BOE Marine had/has the best price I could find (and I did a lot of calling around and googling) . I ordered an HDS-7 yesterday during their sale for US$808 (no maps, no transducer). The sale ended yesterday and their regular price for that unit is ~$850 (Airmar P79 was $104 and Navionics Platinum+ map Maps were $160).
Edit: And I went LSS-1 since, in the US, they were offering a $300 rebate on any HDS/LSS-1 combo purchased by April 30. I see rebates of 30GBP off the HDS and 85GBP off an LSS-1 (if you go the LSS-1 route). Too bad we can't ship US versions to you (I think there's something in the softeare), I will have paid US$1285 (net of rebates) for the HDS-7, LSS-1, P66, & Maps...works out to ~790 Pounds.