The only BO i would actually be willing to pay real money for in the C-Store would be a 100% customizable BO... From Traits, to skills, to texture color, and decide if it had a cat, human or gorn head.
I'd even be willing to toss out 250 C Points for it (that i got for free with my preorder)
Untill that happens... Not gonna happen.
A BO store does sound like a good idea. It could be handled like 'respecs' where you could earn 'purchase tokens' from in game events, EC purchase and by the Cryptic Store. This would also be a way to introduce limited edition officers, such as Liberated Borg Tactical and Science BOs to match the Borg Engineering BO...