How much is confederate 1000 dollar Montgomery worth?

A major percentage of Confederate bills are replicas. Starting about 80 years ago various companies started making photo-reproduced copies on artificially aged paper; they've been sold at gift shops and included in hobby magazines as giveaways.

Around 1973 or so the law was changed to require that all replicas be labelled with the Word COPY, but anything before that has no indication that it's a replica. They're not really counterfeits because there was never any intent to deceive, but a lot of the older ones have leaked onto the market and are often confused with the real thing.

The best way to be sure is to have it inspected in person by a currency expert.