These guys are local for you. Shipping will be steep, for a pair of seats.
Los Angeles Dismantler - Specializing in Used Porsche Parts for Boxster, Cayman & 911
Are your seats broken or just in need of reupholstering? There are a couple of companies that specialize in DIY seat cover sets. I can't find the one I am thinking of just now. Reasonable pricing and the pictures I have seen have been decent results.