The 'CA shop' idea is a good one, but needs a start-up investment.
Maybe this is a potential candidate for 'crowd funding'. The shop would (of course) not charge a mark-up, but it would need working capital to buy stock.
Potential CA liveried items might be...
Flags
PVC Banners
Laser cut car stickers
T-Shirts / Polos / Fleeces
Anything else?
P.S. Long ago, back in the 90's we had the annual CA 'sticker challenge', where we tried to get CA stickers on as many 24h competitors cars as we could. It might be fun to try that again.
The "shop" prices should contain some sort of mark up to cover any admin costs that may crop up. Any left over monies can go to a nominated charity.
Lawnmower Man had some CA lanyards done a couple of years ago, handy together with PVC ticket holders.
Not forgetting CA thermal mugs!