It's possible to replace the boot, but AFAIK not by the regular DIYer. As long as there is not evidence that they have been installed, you should be fine - I've no complaints about BavAuto's customer service.
I'd try Patrick or Yves at BMAParts.com, though - customer service is excellent and prices tend to be much better, even for OEM dealer-ordered stuff. And don't let the online catalog fool you - they can order anything the dealer can get.