Brazil contact 1937's are not going in the $700 range. Most still seem to float $200~$450 depending on condition. They do seem a bit harder to find these days. Last two I saw had been chopped up and modified.
I paid $125 for mine in the early 1990's and I'm not selling it.
My dad has one. His is the genuine military one from the first world war. Great condition. It's a really cool gun. Looks mean as hell, too. Are those prices of 750-1000 for one like my dad has? If so I had no idea they were worth that much.