Dear Ethan:
The "ballpark" for each school is different, and likewise it might be bigger or smaller depending on the parts of the candidate's application (i.e., GPA, recommendations, essays). Keep in mind, an average GMAT score for a school is the
average meaning half the class is above that number and half the class is below. I think you are probably in both of those schools' "ballparks" as you are only 30 points below their average.
A quick way to get a general idea of the "ballpark" for a school is to look at its mid-50% range for GMAT scores. You can find the mid-50% (and/or the mid-80%) range for schools on their websites, in some rankings, and on many b-school informational websites.
Keep in mind, though, if you fall under a school's average GMAT, it becomes more important to have a strong undergraduate GPA, solid work experience, strong essays and interview, and glowing recommendations.
Good luck!
Lisa