Both the NP and AB are great bullets in the 300 WSM, and if you have a good load, there is no need to switch from one to the other. At 300 yards or less, there is no advantage to using the AB with its bot tail design.
My 300 WSM shoots both well, but does prefer the AB (less than 1/2 MOA vs 3/4 MOA), so it is what I use. But I would not be unhappy with the NP, and would not hesitate to use it on any game in NA. I have successfully harvested many animals over the past 35 years with the NP and the AB, and none would have been able to tell you that it was taken with the NP vs the AB. Average shot distance has been 137 yards, and only a handful of animals were taken at beyond 300 yards.
As for cost, the bullet (or even the ammunition) is the least expensive component or item on any hunt. But it is the single piece of the puzzle that determines the final outcome of the hunt (given all other factors have been performed properly). At least for me, good bullet performance (accuracy and good energy transfer to animal tissue through reliable expansion and penetration) is more important than its cost. And no, I do not have a lot of money and must buy wisely; therefore I buy the best that I can afford.
A factor that I do favour in the AB, is that it has proven over the years to be the quickest and easiest bullet to find a load for in all of the rifles and cartridges I have tried it in, and it has been the most accurate in most of them. It has provided excellent on game performance. The NP has never failed to provide at least acceptable to excellent accuracy, and has always provided great on game performance.