Like Ken said, rainbows are only good for spare parts nowadays.
I bought a passenger seat from a 5 door to make good my 3 doors drivers seat. I'd be tempted to make your rainbow drivers seat mint by doing a foam and cover swap yourself, then chuck the rest away. Dull as it seems, you'll be more likely to find someone who will pay good money for a mint drivers seat on its own, than you would someone who wants the lot.