For $2k, it will be tough locating a true quality "Custom" bass. For a true quality "Custom" bass, like you are wanting dollar-wise, you'd be looking somewhere closer to $4k and up.
I'm not suggesting you won't find what you are seeking within your budget, but what is considered a "quality custom" instrument to some doesn't make the cut with others. Who knows, maybe you will come across something on the used market.
At $2k, not sure how many of these do 6's, but check out Lakland Skylines, Ibanez, Yamaha, Washburn, Dean, among a myriad of others. I would suggest you sit down with whatever you decide to go with, play it and make sure you are getting the $2k instrument you'll be happy with.