Cheaper scopes don't hold up as well this is true. But you have to drop down well below the Buckmaster before you will have major issues. The Buckmaster is not a high end scope, but is still a solid scope I'd trust.
With some scopes you might see very minor changes in impact as you change powers. But we're talking very minor differences. I was discussing this with another poster months ago who complaned about brand X scope changing his point of impact when he changed from 9X down to 3X. When we did the math on it there was a difference of about 1/4" at 100 yards. Less than the diameter of most big game hunting bullets.
My solution was this. Zero the scope at the highest power. At close ranges I only use the lowest power setting and 1/4" difference at close range isn't a factor. At anything over 100 yards I'd pass right over all the intermediate settings and go straight to the highest power where it was zeroed.
I've NEVER heard of a scope losing its zero because of changing magnification. Only very slight differences at different power settings.