I do think it's a bubble, and at least partially being artificially inflated by the easy-peasy no-cash handled internet. Like they say though; perception makes a reality. What we see here are the advertised retail prices, and a lot of them are folks who semi-professionally flip high end basses. Common sense tells you those guys didn't pay that much for them. All you have to do is get there first, with cash in-hand, and you don't have to pay the markup.
I'm somewhat amused by the whole thing, now that I have watched it long enough to understand, and a little bit put off too. On one hand I don't like that these things are increasingly out of realistic reach of average working players. On the other, my Series instruments have already doubled in value because of this price drive, and I have none other than the flippersharks to thank for it. That stripped-out Persuader 5 I paid $1400 for 8 years ago... then had to put all new electronics in... I was waaaay underwater on it, and didn't care, because I finally had an Alembic. Well, I'd be stupid to list it for less than $4K today. (that bass ain't worth that, and I'm not selling it!) I also prefer to do biz person-to-person, and cut out the transaction fees. I have found that goes a long way toward closing a deal. I love doing business with people who love these instruments as much as I do. That way, we understand each other better, and quite often, I will make a gentleman's agreement to sell back to them, if they'd like. Again, just me. I'd much rather sell to a player than to someone who just wanted to make another 20-30% on a guitar I had. But hey, whatever lights up their life is cool with me. I just don't carry that gene.
Will the bottom fall out? We'll see.