Well, if a scope has a small enough "sweet spot" that it affects anything important, it's junk. I haven't come across a scope like that in a very long time. What I do see are things like that illustrated in 1858's post: the last little bit of the edges show distortion. This is completely irrelevant, as few people look through the edge of the scope, let alone try to line up the reticle and target in it.
And I'm afraid you've got it exactly wrong, IMO, with your line about "Over a $1k, you start to see the REAL difference and benefits". There is a large difference between a $30 scope and a $300 scope, a smaller difference between the $300 scope and a $1000 scope, and so little difference between a $1000 scope and a $2000 scope as to be irrelevant for the overwhelming majority of shooters.