Cheapest/best source for a Kenwood DNX520VBT?

I've decided on one of these units for my car and planning to buy one from Deutschepart on ebay as their price is reasonable (£600 for a new boxed unit) and they're very well rated but thought it's worth checking here first to see if there's any other better sources. I've had a dig through the forums and aside from a group buy from a dealer I've not seen any other good sources but prices are always changing.

Thanks,

John