I think you're right John, the quotes i've got so far from the main couriers are in the region of $200 - $300 which makes the total costs for importing one from Redline too expensive. I like the concept of this solution rather than a fully fledged half or full cage so might use my contact to fabricate something similar, with a few minor mods to my specification. I've been reading the rear seat delete thread as well and will probably go with that too and get an interior upholstorers to make up a peice of carpet that press-studs in place so I can put the seats back in when I come to sell the car on again. I think the weight trade between the rear seat delete and bolt in 'cage' will probably be nett zero - unlike a proper half or full cage which would add alot more wieght - and i'm sorry, but i'm not getting rid of the A/C or the power steering!!
I've got alot to be getting on with over the next few months!