I've just changed mine, great fun !, luckily enough I got one of another car being broken, I did check online and autodoc were showing them available at around £130.
I'm just in the process of replacing my power steering pipes due to a leak on the lower pipe where it has rusted through. Trust me this is a job to be avoided if possible, get under there now and coat these pipes with you favorite rust preventer - waxoyl, dynax, chain saw oil or whatever, it...
Also I did forget to mention, look up the spec for the fitting position of the upper mounts for the harnesses as these must be high enough so that they do not compress your spine in an incident, you can find this on youtube
The seats and harnesses should be easy enough to sort yourself. You do need to use the original seat fixings and I would advise fitting runners, this is because when you strap yourself in with the harnesses they should be tight so that they hold you firmly in the seat. This allows you to move...