The main cost input is presumably ram. They are passing it through.

If everything on the board but the ram costs $30, and ram is going from $10/gb to $20/gb, then they have to change the price $50 -> $70 to break even on the 2gb board, and $190 -> $350 for the 16gb board.

In other words, the raspi is now priced like a stick of ram with a bonus computer attached because ram is massively more expensive than the rest of the computer.