What Type of Budget Should You Set on Your Test Prep?

[roethlisburger]

Another thing to consider is that “an average increase of 50 points” says little, since an increase from 1050 to 1100 is not the same as from 1400 to 1450, and the difficulty in raising an SAT from 1400 to 1450 is much higher than from 1050 to 1100.

I somewhat disagree with this. The SAT tests are by design on a normal distribution. Getting an average ability kid to score at the +1 standard deviation level is as impressive as raising a +1 standard deviation kid to +2 standard deviations.