Can't stand car park *****, I don't see why people have such issues with them though, it's not like it's difficult to drive round them and how hard is it to put your hand on the edge of the door if you're not entirely certain you can open it without making contact with the car next door?
eBay would be your best bet, there's a couple being broken on there who'd be able to sell you a door.
None of them metallic yellow (tribu? or chrono yellow? (i dind't think chrono was metallic) last time I looked so you'll then have painting costs on top of it.
If no claims is protected then i'd just let the insurance company sort it out, much less hassle and almost certainly cheaper.