Its hard to believe that someone who has been into Bitcoin for such a long time never signed up to this forum and participated in it especially considering you have an incredible amount of money stored in there. If you can remember the sort of characters you used then you could potentially bruteforce that hard drive and I think it would be worth investing a few hundred bucks in that.
OP's account registration date was June 09, 2011 so OP was definetely around during bitcoin's early days.
However the claim is dodgy.
If not impossible, maybe OP should try to decypher or find someone to decypher the hard drive, rather than selling it for bits on the bitcoin.
It could be any random cyphered hard drive that you buy and $390 is expensive for a hard drive.
Not saying this is what happened, but another possibility is the BCT account could have been resold.