quick question on haste vs mastery

I was just wondering if their was a point where mastery becomes more powerfull over haste once u get a lot of haste or if haste is still stacked and better to get always
In current end-game gear this doesn't really happen, but you're forced to go lower on haste anyway because a lot of the BiS heroic gear doesn't have much haste on it. Get yourself to around 1800 haste or so and you'll be fine.
Keep in mind that even that whole concept of mastery over taking haste is off in that they are so close to each other as dps stats already. the difference between them is .02 as a stat weight. So really while you still want haste over mastery it's not at times worth it to ignore an upgrade that mastery on it just because it lacks haste. Haste = 1.92, Mastery = 1.90.

What this means is an item that haste 102 Mastery is more dps than something that is 100 haste as dps ratings go. when you also add fights that favor add swapping and burst aoe then Mastery goes higher up in value for that exact fight. Truly I'd say while you prefer haste it's not worth ignoring other stats. Crit is worth 1.68 as a stat weight so it's sacrificed in most areas to become haste. But overall I wouldn't think of it as mastery being far behind haste. It's actually extremely close compared to most classes and specs class weights.