Thinking airplay-wise

First up, sorry if this is the wrong thread!

Second, I'm looking for a nice pair of speakers. Nothing Audiophile quality, but something thats a bit better than my current £25 iPod dock. I'm thinking of looking at something thats airplay capable, but my friend also told me theres something you can get that can make speakers airplay-compatable?

I understand you can do something like this using the Airport Express, but can that be used with any speakers with an Aux or?

I'm looking at something like the Zeppelin Mini if I can airplay it, otherwise I know nothing for airplay. Is the Sonos any good?

Thanks!