The headjoint of a flute is a key part which significantly affects the sound quality and timbre of the instrument - it is by no means an “adapter” to the rest of the instrument. It is common in fact to buy flutes in separate pieces, with the body by one manufacturer and the headjoint by another. And $2000 for the headjoint and $4000 for the body (Australian dollars) would be a pretty standard price for a good-quality student flute which would see someone through a performance diploma.
