The Damier Speedy is 30% more than the regular mono speedy. 30% is the normal mark up (average) for a special order bag. And approx wait time is 3 months. I have had mine about a year now and it is my absolute favorite bag. Between the damier canvass and the dark leather it is a total worry free bag !
Although I have been hearing rumors that they will start making in regular production a damier speedy 25 ? If so, then definitely wait till it comes out. I think they are talking about a summer release for this? (I know there are others who know more about this and can chime in).
Also this ebay seller is a lovely person and wonderful to do business with (and no it's not me ! LOL!)