If you're wanting a good C3 Jay, then buy one freshly imported.
EMC Performance are the guys to speak too. I nearly bought an immaculate 1989 airdam C3 from them a few months back. Then the wife decided we are moving house so that plan got thrown out.
Anyway, the cars he imports are immaculate. A good 80/81 C3 from him will be just shy of £11k.