Many box blades look alike. That could be a King Kutter (but the wrong color), Bush Hog, Big Bee, Howse or any one of a number of other manufacturers. If the seller is sending you the pics, see if he can get one that shows the outside of the end plates or an ID plate.
That looks to be a light or medium-light duty box blade. Around here in used condition with all the scarifiers included and with no bends or wrinkles, it would bring $450 - $500.