Carvin is nice, they are expensive in some cases, but for a custom made guitar, it's some good stuff.
schecter does make one, it's nice and affordable, make sure if you get one, get it with the actual seymour duncan pickups and not the designed ones.
fender makes one, it is usually made in japan and sold in the states under custom order,
there is a few companies that make some cheaper or affordable ones.
depending how serious you are about wanting a 12 string will have an effect on the price.
Jay Turser has a SG, a Strat and a couple of other 12 string electrics all $200 - $400
the electronics are ok, not great.
Epiphone made a 12 string les paul a few years ago, I don't know if it is still available, it was $500 new.
Davidson makes one for $300
I had an older Epiphone acoustic that was a 12 string with electronics in it, not bad if you wanted to plug it into an amplifier,
a great one is a rickenbacker, but $2,000 and up is a bit too high.
fernandes in Japan makes a clone of the rickenbacker for $700 , they sell it under the burny name and under the fernandes name,
good luck
