Have you considered some active (powered) speakers and hooking them up to an airport express?
I was trying to find several docks for my house so I could hook them all up and play music through the house in sync. I looked at tonnes of docks and whilst something like the zep or sonus do sound a lot better than the alternatives you just can't beat a pair of active speakers.
If you do want a dock, I bought a Philips dock, I think it was this http://www.amazon.co.uk/PHILIPS-DS85...724356&sr=8-15
and it has a fantastically rich, full pleasing sound for the kitchen. The mrs was very impressed and whilst I paid a bit more than current prices it was a bargain compared to some of the more expensive docks when comparing sound. Zep looks amazing tho.