My cat bolts look pretty bad. I expect they will shear.
If they had to be drilled out it looks like you could just put a bolt through the drilled out hole rather than re-tap the hole.
Apart from those 4 bolts the rest of the system just hangs on rubber loops.
A Vx TC system will be about £75 a side for mid-sections and £54 for the backbox (facelift 2.5 estate) all prices plus VAT. Total, all in £240.
However Darren Flynn (up Newcastle way, and I hope I got his name right) got a complete pre-facelift estate system fitted for around £174 (bargain).
So shop around in the first instance, and it might be worth getting a local garage to fit whatever you get because 2 people and a ramp would make life a lot easier.
For Bosal check these people out:
http://www.bodyshopwarehouse.co.uk/bosal/default.htmAnd
http://www.buypartsby.co.uk/Have been used successfully by a couple of members of my family.