I guess it isn't surprising that he would say what he needed to to get you to buy, but as others say, the average purchase isn't important, the only correct number is the number that is right for your family based on how often you want to go, how long you want to stay, what size accomodations you want, and how much you are willing to pay at that time (for me that last one was my number one concern!) We bought 200, which is probably slightly less than ideal but will work for us. We would like to stay most often in 1 bedrooms for about a week and go every 12-18 months. To comfortably do this we could probably use a few more points than we got, but for now, this will work very nicely-- since we're starting out with a point surplus we can slowly work through the banked points, and mix it up with the season we go, and occasionally do a studio or sun-Fri stay to save points. In a few years I could see us wanting the 2 bedroom. But we will probably never go more often than once a year. Right now we just didn't want to spend any more than the $$ for 200.
I'd advise you look at your number and map out your ideal vacation schedule / rooms for the next 3-4 trips-- be realistic. Then if you still think you bought too many, I think there is still time to do a new contract. Good luck.