It was to be expected in anticipation of the GeForce GTX 650 (Ti) release. AMD's Radeon HD 7700 and 7800 series graphics cards keeps dropping. It's not an official price cut, but rather AMD's partners lowering their prices. Starting today, AMD Radeon HD 7850 1GB costs $159 (after rebate), whereas the 2GB version carries $189 official price-tag. The AMD Radeon HD 7770 GHz Edition graphics board now has manufacturer suggested retail price of $119.
AMD and its partners specifically reduced price of sub-$200 graphics boards to improve positions in the most popular segment of graphics boards.