I'm not going to judge...
So, IF I was going to do this as cheaply as possible, I'd start with a pair of these eBay seats and then have a local upholstery shop re-cover them in grey and add the plaid inserts.
Total: $490 for the pair of seats + ~$200 ea upholstery = ~$900 for a very custom look.
GT RACING SEATS BLACK FRP 996 997 GT2 GT3 RS BUCKET 911 PORSCHE VW AUDI SALE | eBay