I have never seen an Exige in white, Bell and Colvill tell me they sold a couple of them but whoever owns them seems to be keeping the fact close to their chest!
If anyone has any I would love to see some pictures.
You could try Lakeside Engineering, I know they put one back together for somebody (following a Dingle Dell incident I understand). I was at Silverstone when they were there (not overly chatty folk).