Component costs (exotic tops, pickups, Fodera bridge, Pope preamp etc) are certainly higher for the Fodera than the Carvin but that's not primarily what drives the price difference. It really is about the difference between the cost of a factory built bass and a handmade one. You are paying for the expertise of a trained luthier/builder and the ability to custom design your instrument. Carvin allows a wide variety of options, but they are not custom instruments in the true sense. And their construction method allows for a greater number of instruments to be produced with fairly tight tolerances.
Jason at Fodera has said a number of times that they spend more time on the inlay on the headstock than it takes factories to build entire guitars. Fodera spends more much more time per instrument, has a small and very experienced crew that is almost certainly paid a much higher wage than Carvin workers and in general have a much higher overhead per instrument due to the way they choose to do business.
Whether that personal touch, attention to detail, and decades of experience of hand building instruments (and interacting with high level musicians in NYC for their feedback) and of course the playability, aesthetics and tone of the finished instruments are worth their price tag to you is an individual decision.