I don't think a 97 key is "cheap" or "cheaper". Just about scared the stink out of me when I found out what my dealer was going to charge me! But then I quickly discovered my dealer charges 2x or 3x the retail price on every single thing that Porsche owners can't live without... keys, radiator caps, oil, filters, etc.
John, I know you are in the UK, but you may find that buying a key head and key blank (and that manual for the car that you really do need) from Sunset in Oregon would be your cheapest way out.
Your British pound is worth a lot on this side of the pond, and for such a small box, the shipping costs won't be absurd.
http://www.****************************************************.com/porscheatcost.php
They're running a sale on key heads right now.
Had you posted this a month ago, I could have brought them to you... I was in the UK for 10 days for work with nothing to do and a Britrail pass. I could have delivered them to you.