the google/samsung nexus s has officially received the ics update, being a google phone and all. although google have pulled the over the air update for whatever reason, you can still install it 'manually', as google's servers are still hosting the update. the nexus s was Ł200 sim free at carphone warehouse a few weeks ago - your local shop might have a few left.
Idle speculation time here.
Does anyone have an idea as to what the cheapest phone running ICS as stock is? I know that the denizens of this thread tend to be the kind that think nothing of slapping on two ROMs before breakfast, but I'm thinking more along the lines of a phone for my missus that I don't have to mess about with.