For sure mate. Wayyy too much ... It cost me around 3k. 1500 quid roughly for the Insurance (you can do Black Box as it may be slightly cheaper but it prevents you from being naughty). So maybe look for a car no more than 2k.
But the car that are 2k look like genuine crap they look like they will breakdown in the middle of the motorway
Why do you want an insignia then? Probably the most boring grey car in existence. They're not good cars... We have had many issues with the rental insignias. We call them the Vauxhall Insignificant.