Hi
I have had my impreza MY99 for around 6 months now, and I got it for £2000. Admitadly the car had 97,000 miles on it and 7 owners lol, but I can honestly say that it feels like new (best car I have had).
The only problem with the impreza is the fuel consumption, but you should not be thinking about that if you consider a scoob. I work in town so I can get roughly 80 miles from 20 litres of fuel (18-20 mpg) I did do a 400 miles trip to yorkshire and back a few months ago, that was a tank of fuel + a quarter so in all around £80 at the time.
Persinally if I was looking for another impreza I would buy it of a forum member (not limited to this one) as the chances are they have looked after it, and you know the history of the user (previous posts etc)
For the insurance I went with direct line, it started off around £700 (5 years no claims) but then went down to £330 when I fitted a tracker, so it may be worth getting a qoute of them.
Good luck in the search for yours.