supply and demand, and costs associated with initial line switch and programming of a short run.
plus bf4 limited edition package etc.

price will be $650 w/o bf4. for near 7990 w/o crossfire perf.

in the new year we'll see nvidia slower 780GTX price to ~500's and the 290X will be in the ~450 shortly after. when large production runs of the line can occur.