I am afraid that I have not read the complete thread, so forgive me if I am repeating what someone else has said.
For me, an expensive bass is one where the difference between what I paid for it and what I sell it for is painfully negative. Brand new G&L and US Music Man Sub (stripped, painted and fully installed with Bongo electrics), I am looking at you.
Given the BC long term loan, sell it for what you paid for it scheme, most basses are kind of cost neutral in my way of measuring expensive.