Update: see also the Nikon D750 specification listed on the same website.
When you search for “D750” at German price compare website idealo.de, you will get three results from Calumet Photo Germany with the following prices:
The D750 probably already exists in the Calumet’s inventory system and this is how idealo.de was able to pull it out and display it on the Web.
As usual, expect US prices to be lower – I initially reported the price to be around $2,500.
The official announcement should be tonight (Wednesday) or tomorrow night EST (Thursday or Friday early morning GMT).