avnut said:
This is my question as my router cannot be wired to the imac(without considerable grovelling) and so hence the need for wireless.
Wireless storage (ie your iMac) is NOT actually a supported solution by Sonos, they like the storage to be wired. That isn't to say it wouldn't work but if you have streaming problems and your storage is wireless Sonos will likely point the finger at that and there isn't anything they can do to help with that problem.
For your budget though you'd be able to add a small NAS to put the music on, that would be wired and would give you the benefit on not needing the iMac switched on when you're listening to music (which, trust me, WILL get annoying after a while).
The Play:5 is £349, if you're lucky you might get the bridge thrown in for nothing (that deal seems to come and go), the dock is £99, so that's £800, which is plenty for a suitable NAS. If you go with the Play:5s you can add another one later and create a stereo pair in one of the rooms, which gives a big improvement in the sound.
I'd question why you think you need a dock though, unless it's for visitors?