£400!!!!
I done mine for £17, £13 for plastic adaptor, and £4 for keys.
First of all you need some keys (got mine from MotorWorld)
Then you need to undo the 4 little allan key nuts in the 4 corners of the cassette player.
Then place one key between top and bottom right hand side, and the other key top and bottom left hand side. If you push these in all the way you should hear a little click. Then when they are fully pushed in pull the radio out, grip the little shelf thing the vauxhall radios have.
If you are fitting another Vauxhall brand CD player go ahead and slot it in, then replace the little nuts. If you are fitting another CD player like a smaller regular sized one from Halfrods or something, read on.
Inside there is now a cage which held the radio in place. This can be undone by unscrewing the torx screw that is situated at the back of the cage, then once that is undone, you need to bend the cage in order to get it out.
Then you need a plastic adaptor which will allow a regular cd player to fit. I bought mine from MotorWorld, £13 for a bit of plastic!!!!
Fit your bit of plastic into the hole, then from there, just do what you would do to fit a cd player into any other car without those massive radios! (fit the new cd player cage and connect up then slot in)