We used it to take the edge off of a few steers, depending on the animal, we would start with 20 3mg pills and then adjust from there, to dopy, drop to 15 pills, still a little dopy drop 5 more pills and so on until it is right. No change or little change in disposition, bump up by 5 pills and watch, no change do it again.
We bought them at Walmart or any local drugstore, just looked for sales, some store or brand is always offering 2 for one.
Just make sure you check the mgs, sometimes there are different dosages. So the cheaper one may be because it is a 1mg pill so you would need 3 times as many.
Once she gets used to being handled you may be able to take her off of it, we've had both types, the animal that settles down and the ones that need it every time you haul them to a show, and then one or 2 who just got it every day for the life of the project.