I bought a Pioneer 4500BT a little while ago, was £90-100. Seems good for the price, has ipod connectivity and bluetooth. Display is a bit basic - just single line and block style digits, but does the job.
I have more expensive Pioneer and JVC units in other vehicles, and of the 2 (no real experience of other manufacturers) Pioneer is my favourite - just seem better to use, so would recommend Pioneer as a brand to go for at any price point I guess, although Alpine are very popular too.