I'd guesstimate not much more than a dozen made...(Westfield might confirm)
They reckoned they were going to build 30 at the time (98->99), but I'm not sure they found 30 people willing to spend £40k on a 'kit car'...(Most went and spent that sort of money on an R500...

)
Rare as the proverbial - Powered by a 190 VHPD 'K' series, and weighing in around 400-450kg...
Carbon fibre chassis would worry me - I'm sure it's well tough/torsionally stiff, and the force required to irreparably damage it would almost certainly write off an Elise etc...
...but I just don't know if C/F ages as well as more conventional materials - All the FIA TGP F1 cars from the '80's need to be crack tested & certified every year before they can race...
Sure - I understand the cars I mention above are all 20+ year old racers, and subjected to way higher stresses...But it would be something I'd need to consider....
If it were my money, and I was after something like that, I'd buy a Caterham Fireblade...Sub-400kg's anyone?!
